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Excerpt from my MULTIPLEX ADVANCED DIAGNOSTICS training in 2002.
The entire STUDENT GUIDE is a large file but this is the CAN bus generalization.
The attachment says to remove the ABS/TC CM (Anti-lock braking / traction control module). Can I just unplug the connectors (the larger main one and the smaller one below it) or do I have to completely remove the module?
Is that what appears to be a VIN at the top of ECM label? SAJDA42C41NA19009? Is that supposed to be the VIN of the vehicle it was installed into? Because my VIN is NOT that.
Your ECM is also a replacement from a salvage yard. It could be the same vehicle that the TCM came from, but we don't know.
Motorcarman can explain VCATS far better than I can, but for the purposes of your current situation, think of VCATS as firmware stored in various computer modules in your car that all must be speaking the same firmware language (VCATS version), and some of which must be programmed with your vehicle's correct VIN.
In my experience, you can swap TCMs without the need to reprogram them as long as you use the same part number and VCATs version as the original TCM.
If you really need to remove the ABS module, it can be removed from the ABS modulator valve assembly without disconnecting any brake fluid lines by removing some screws and carefully bending the brake pipes to allow the module to be drawn off of the modulator valves. I'm sure there are good DIY instructions somewhere in this forum or at the Jag-Lovers forum. I know jagrepair.com has a couple of documents showing how to cut the cover off of the module so the solder joints on the circuit board can be reflowed and supplemented with new solder. I don't recommend the method of using a hole saw to cut an opening in the case and just repairing the solder on the two large pump motor pins. I have repaired a lot of these modules, and on every one of them, at least several of the other, smaller solder joints were cold, cracked or starved, which can lead to various malfunctions besides C1095. For example, all four wheel speed sensors connect directly to this circuit board via the larger electrical connector. So I carefully cut the cover off, reflow and supplement all of the questionable solder joints, then glue the cover back on with silicone sealant. This repair is usually good for the life of the vehicle.
Disconnect the ABS / TC CM.
Reconnect the battery negative cable and switch the ignition to position II.
The following warnings should activate:
XJ and XK with traction control
MILs: ABS; BRAKE; AMBER
LEDs: TRAC switch
Message center display: TRACTION CONTROL FAILURE; STABILITY CONTROL FAILURE
XK without traction control
MILs: ABS; BRAKE
LEDs: ASC switch
Switch the ignition OFF and disconnect the battery negative cable. Reconnect the ABS / TC CM.
Reconnect the battery negative
Your ECM is also a replacement from a salvage yard. It could be the same vehicle that the TCM came from, but we don't know.
So it sounds like I bought a piece of scrap metal that has had exhaust issues, given the fact that at some point the cats were replaced with ones that did not have studs and bolts were used, the TCM and ECM were both replaced from some salvage yard and God knows what is inside the ABS module. What amazes me is that the car runs great. With the new battery it starts right up, drives great, shifts great. It's just an electrical nightmare. I remember back in the day (of Lucas electrical equipment) no one bought a Jaguar because, even though they looked beautiful, they were electrical horror shows. Sounds like nothing has changed.
Motorcarman can explain VCATS far better than I can, but for the purposes of your current situation, think of VCATS as firmware stored in various computer modules in your car that all must be speaking the same firmware language (VCATS version), and some of which must be programmed with your vehicle's correct VIN.
In my experience, you can swap TCMs without the need to reprogram them as long as you use the same part number and VCATs version as the original TCM.
I guess the question here is how does one know what VCATS is in the TCM and ECM? Is there some scanner, plug, computer or wizard that can tell me this?
The ABS module can be removed from the ABS modulator valve assembly without disconnecting any brake fluid lines by removing some screws and carefully bending the brake pipes to allow the module to be drawn off of the modulator valves. I'm sure there are good DIY instructions somewhere in this forum or at the Jag-Lovers forum. I know jagrepair.com has a couple of documents showing how to cut the cover off of the module so the solder joints on the circuit board can be reflowed and supplemented with new solder. I don't recommend the method of using a hole saw to cut an opening in the case and just repairing the solder on the two large pump motor pins. I have repaired a lot of these modules, and on every one of them, at least several of the other, smaller solder joints were cold, cracked or starved, which can lead to various malfunctions besides C1095. For example, all four wheel speed sensors connect directly to this circuit board via the larger electrical connector. So I carefully cut the cover off, reflow and supplement all of the questionable solder joints, then glue the cover back on with silicone sealant. This repair is usually good for the life of the vehicle.
If I were going to do this I'd remove everything and open up the assembly and do the resoldering properly. I've seen videos that say there is a way to "bend the brake lines out of the way" but this is only asking for more trouble in my opinion. You just know one of them is going to kink or brake and now you're off to replumbing everything. Is there a way to determine if the issue is being caused by the plug or the wires attached there to, or a bad solder joint?
Disconnect the ABS / TC CM.
Reconnect the battery negative cable and switch the ignition to position II.
The following warnings should activate:
XJ and XK with traction control
MILs: ABS; BRAKE; AMBER
LEDs: TRAC switch
Message center display: TRACTION CONTROL FAILURE; STABILITY CONTROL FAILURE
XK without traction control
MILs: ABS; BRAKE
LEDs: ASC switch
Switch the ignition OFF and disconnect the battery negative cable. Reconnect the ABS / TC CM.
Reconnect the battery negative
OK, assuming I have to replace these cats. How can I actually know which one is bad? Is that heat test, where you measure the temp of the area before the cat and then the area after the cat and see what the difference is, the way to do it? Or do you just have to take them off? With all the wires, sensors, monitors and computers in the car shouldn't something pop up on the OBD2 or the car's little dash message screen that says "Hey, your bank 2 CAT is bad!"
Another question regarding replacing the CAT. Since the only thing they do now at the smog station is check to see if the monitors are OK and not INC how does the car (and monitors) know if f there is a C.A.R.B. compliant cat on there or not? What exactly is being measured if all they check is the monitor and the monitor (wherever that is on the car) is simply looking for a working cat.
Please excuse the stupid questions but frustration and lack of knowledge and a specific method to fix a given problem is causing my brain to overload.
Joe
Generally speaking, the downstream O2 sensors, after car warm-up, should show a pretty stable 0.6 volts. This indicates that the cat is functioning as it should be. IIRC, your RH one was showing randomly fluctuating numbers. Both of mine are doing that. I think this indicates a bad cat.
Another method, mentioned above and I may have mentioned it also in a different thread, is to check the inlet/outlet temps of the cats. The outlet should be quite a bit hotter than the inlet. This can be done with an IR gun-style thermometer. In my case, the RH cat outlet shows a temp barely above the inlet. The LH is above, but I'm not sure it's enough.
Non-foulers were mentioned. I tried a couple of sets and it made matters worse. At speed the downstream O2 sensors show 0 volts.
Interestingly, my CCM will set even though the cat monitor won't.
Switch the ignition ON to position II and observe the Mils.
Switch the ignition OFF and disconnect the battery negative cable. Disconnect the ABS/ TC CM.
Reconnect the battery negative cable and switch the ignition to position II. The following warnings should activate:
XJ and XK with traction control Mils: ABS; BRAKE; AMBER
LEDs: TRAC switch
Message center display: TRACTION CONTROL FAILURE; STABILITY CONTROL FAILURE
XK without traction control Mils: ABS; BRAKE
LEDs: ASC switch
Switch the ignition OFF and disconnect the battery negative cable. Reconnect the ABS/ TC CM.
Reconnect the battery negative cable and switch the ignition to position II.
It results in the following:
The only light that comes on when I reconnect the ABS plug (after disconnecting/reconnecting the battery) and move the key to position 2 is the Check Engine light, (or MIL as I think it's referred to as) which goes out as soon as I start the car.
The instructions go on to say that I should move the Transmission selector though all the gears to see what lights go on. When I do this only the P and N lights light up. R, D as well as the 2, 3, and 4 on the J gate do not light up. From what is said in these instruction it seems to mean that CAN is not communicating between the TCM and the gear selector module.
Would this have been the cause of the prior fault codes regarding the "CAN transmission control unit to engine control unit malfunction"?
I also think there is a high chance you have one or more bad cats.
The tough part, as you ask, is how to figure this out (if one is bad, and which one, or even if both are bad).
From what I read on the internet (!) about California, the smog test only uses the car OBD2 system for post 1999 cars (or thereabouts) and no tailpipe measurements are performed.
So the test must rely on zero emissions related error codes, monitors all set, and possibly also digs into OBD2 mode 5 or 6 data to get more details on the tests the engine control unit performs.
Unless you had the Jaguar diagnostic scan tool (IDS in this case), or a third party tool that supports the proprietary Jaguar information, then I doubt you will be able to decode any of the mode 6 information, even if you can get it.
- although I have not looked into it personally, but on a quick search I found no useful information available on Jaguar OBD2 mode 6 for X100. Maybe there is data out there?
- so trying to get mode 6 data is a rabbit hole best avoided (but the CA smog probably uses it, and it may well tell you which banks have issues, if there are issues)
An idea for an alternative - probably no good but whatever....
If you were to get a tailpipe emissions test [ like they still do in Colorado :-(, and they evidently also do for pre-99 cars in CA ], then if the cats were working well, I would expect something like :
However, if you cats were no good, I would guess the results would be something like:
HydroCarbons (HC) much more than 0.25
Carbon Monoxide (CO) much more than 2.5
Nitrous Oxide, etc. (NOx) much more than 1.0
because the purpose of cats is to reduce the emissions of these gases
So if you could get a station to do a tailpipe test (like the pre-99 cars have to do) and get these results (if they could provide them, this is what they report on in Colorado) , that might prove a useful diagnostic.
- but I have no idea if the pre-99 CA tests measure these things, or if it is more than anyone's life is worth to help someone out and run the test
This at least might be better than driving another 500 miles and hoping for the best.
IMHO, the canbus and related possible issues are not relevant to the cats issues, and would be best put on one side for now, given the clock is ticking
- if the car is driving, and the gearbox shifting, and no warning messages, then there is nothing terrible happening right now
- also (but again not a priority right now relative to the cats), now knowing that both the TCM and ECU have been replaced is weird - I hope that the car has not spent anytime as a submarine, but rather was sprayed with a parts cannon by the previous owner trying to fix stuff)
I also think there is a high chance you have one or more bad cats.
The tough part, as you ask, is how to figure this out (if one is bad, and which one, or even if both are bad).
Exactly my concern Chirpy. Given that removing and replacing the cat, or cats, is going to be a royal pain in the butt, and expensive, it would sure be nice to know A/ if they are bad, and B/ if one or both are bad.
From what I read on the internet (!) about California, the smog test only uses the car OBD2 system for post 1999 cars (or thereabouts) and no tailpipe measurements are performed.
So the test must rely on zero emissions related error codes, monitors all set, and possibly also digs into OBD2 mode 5 or 6 data to get more details on the tests the engine control unit performs.
That's correct Chirpy. All they do for my car is hook up their OBD2 and see if the monitors are "OK".
Unless you had the Jaguar diagnostic scan tool (IDS in this case), or a third party tool that supports the proprietary Jaguar information, then I doubt you will be able to decode any of the mode 6 information, even if you can get it.
- although I have not looked into it personally, but on a quick search I found no useful information available on Jaguar OBD2 mode 6 for X100. Maybe there is data out there?
- so trying to get mode 6 data is a rabbit hole best avoided (but the CA smog probably uses it, and it may well tell you which banks have issues, if there are issues)
My ODB2 scanner is an iCarsoft LR 2.0 which is Land Rover/Jaguar specific. Although I'm not sure what "mode 6" is.
An idea for an alternative - probably no good but whatever....
If you were to get a tailpipe emissions test [ like they still do in Colorado :-(, and they evidently also do for pre-99 cars in CA ], then if the cats were working well, I would expect something like :
However, if you cats were no good, I would guess the results would be something like:
HydroCarbons (HC) much more than 0.25
Carbon Monoxide (CO) much more than 2.5
Nitrous Oxide, etc. (NOx) much more than 1.0
because the purpose of cats is to reduce the emissions of these gases
So if you could get a station to do a tailpipe test (like the pre-99 cars have to do) and get these results (if they could provide them, this is what they report on in Colorado) , that might prove a useful diagnostic.
- but I have no idea if the pre-99 CA tests measure these things, or if it is more than anyone's life is worth to help someone out and run the test
That was going to be kind of a last resort. My local station is a one man operation and I'm getting to know the guy pretty well, given the fact that I keep showing up in British Racing Green XK8 with the top down for the test and him telling me "you have to drive it around more". Maybe I can convince him to do an actual tailpipe test just to see what it shows.
This at least might be better than driving another 500 miles and hoping for the best.
IMHO, the canbus and related possible issues are not relevant to the cats issues, and would be best put on one side for now, given the clock is ticking
- if the car is driving, and the gearbox shifting, and no warning messages, then there is nothing terrible happening right now
- also (but again not a priority right now relative to the cats), now knowing that both the TCM and ECU have been replaced is weird - I hope that the car has not spent anytime as a submarine, but rather was sprayed with a parts cannon by the previous owner trying to fix stuff)
That is what I'm hearing from several people. However, I'm also hearing that the monitors will not clear/reset if there are any fault codes. Also, it felt like I was actually doing something when I took the plugs off, cleaned them and put them back and ran the test procedure and go the result that Jaguar says means that the ABS is talking to the TCM. Now I just have to get an answer regarding the lights on the selector not lighting up. From what I've been researching it seems to be one of the two bulbs in the selector cover set up. That's going to wait until after I get the monitors reset. I'm going to throw a multimeter on the OBD2 port tomorrow morning and see if I get the correct reading to confirm that the CAN is working between the ABS/TCM/ECM. The lights in the selector can be dark for now. Then I'll throw the OBD2 on it again and run it to see if those codes are really gone. If I get no codes I may go try the drive cycles again. It's the weekend and traffic won't be as bad so I might actually be able to do them without getting run off the freeway.
Oh yeah, I ordered one of those inferred heat sensors to try and measure the temps for the CAT.
I meant to attach this document earlier. It's the diagnostic guide for your ZF transmission, which includes definitions and the published possible causes of P1797 and P1799.
P.S. Well, I can't get the document attachment script to function. I'll try to attach the document tomorrow.
That is what I'm hearing from several people. However, I'm also hearing that the monitors will not clear/reset if there are any fault codes. Also, it felt like I was actually doing something when I took the plugs off, cleaned them and put them back and ran the test procedure and go the result that Jaguar says means that the ABS is talking to the TCM. Now I just have to get an answer regarding the lights on the selector not lighting up. From what I've been researching it seems to be one of the two bulbs in the selector cover set up. That's going to wait until after I get the monitors reset. I'm going to throw a multimeter on the OBD2 port tomorrow morning and see if I get the correct reading to confirm that the CAN is working between the ABS/TCM/ECM. The lights in the selector can be dark for now. Then I'll throw the OBD2 on it again and run it to see if those codes are really gone. If I get no codes I may go try the drive cycles again. It's the weekend and traffic won't be as bad so I might actually be able to do them without getting run off the freeway.
Oh yeah, I ordered one of those inferred heat sensors to try and measure the temps for the CAT.
Don't forget to post your downstream O2 sensor voltages. They're useful in diagnosing the cats.
BTW, the lights on the shifter do burn out. A couple of mine went south and joined the enemy. The bulbs require soldering to replace them, so I sent the assembly off and had LEDs soldered in instead.
Don't forget to post your downstream O2 sensor voltages. They're useful in diagnosing the cats.
BTW, the lights on the shifter do burn out. A couple of mine went south and joined the enemy. The bulbs require soldering to replace them, so I sent the assembly off and had LEDs soldered in instead.
Hey Jag,
I doubt I'll get time this weekend to run those numbers. The twin grandson and granddaughter have a birthday party today and tomorrow is Mother's Day which we are hosting at home. I'll be driving it to the party today and tomorrow it will sit in the driveway and look pretty. Maybe next week.
I read this thread about the lights and thought "who the hell designs a simple think like a light under the gear you're in and makes it THIS complicated!!!!" https://www.jaguarforums.com/forum/x...-switch-82482/ This is EXACTLY I'm going to stick to old (at least or almost as old as me), simple (carburetor, engine, spark plug), reliable (insert key, turn key, drive) truck after this.
Hey Jag,
I doubt I'll get time this weekend to run those numbers. The twin grandson and granddaughter have a birthday party today and tomorrow is Mother's Day which we are hosting at home. I'll be driving it to the party today and tomorrow it will sit in the driveway and look pretty. Maybe next week.
I read this thread about the lights and thought "who the hell designs a simple think like a light under the gear you're in and makes it THIS complicated!!!!" https://www.jaguarforums.com/forum/x...-switch-82482/ This is EXACTLY I'm going to stick to old (at least or almost as old as me), simple (carburetor, engine, spark plug), reliable (insert key, turn key, drive) truck after this.
Yes, the illumination module is separate to the gearbox and is on the CAN network (it sits between the transmission and the instrument pack). As some of the lights are working it does seem to be connected to the CAN network ok, but still worth checking.
The real problem you have is that you bought a car which someone prior to your ownership bodged together with second hand parts that may or may not have been the right ones. The fact that the TCM was sitting loose doesn't suggest a particularly high level of attention to detail, or maybe they just said f*** it and moved the car on. Once the car is all up and running, maintenance isn't that hard. Personally I would never go back to carbs after computerised fuel injection (although maybe I wouldn't miss the downstream O2 sensors and the cats if they could be avoided). Your other problem is the annual inspection itself. Where I live they put a probe up the exhaust pipe and don't connect anything to the OBD, so the car either passes or fails, but can't fail just because a monitor didn't set, for unknown reasons.
Yes, the illumination module is separate to the gearbox and is on the CAN network (it sits between the transmission and the instrument pack). As some of the lights are working it does seem to be connected to the CAN network ok, but still worth checking.
The real problem you have is that you bought a car which someone prior to your ownership bodged together with second hand parts that may or may not have been the right ones. The fact that the TCM was sitting loose doesn't suggest a particularly high level of attention to detail, or maybe they just said f*** it and moved the car on. Once the car is all up and running, maintenance isn't that hard. Personally I would never go back to carbs after computerised fuel injection (although maybe I wouldn't miss the downstream O2 sensors and the cats if they could be avoided). Your other problem is the annual inspection itself. Where I live they put a probe up the exhaust pipe and don't connect anything to the OBD, so the car either passes or fails, but can't fail just because a monitor didn't set, for unknown reasons.
Good luck and keep at it!
Morning Dibbit,
I agree, it does seems like someone really screwed up this car. What, to me, is so frustrating about "newer" cars is that it is almost impossible to find a definitive answer to these "electronic" issues. It's almost like the manufacturers were given a set of requirements, they fiddled with wires, sensors, computers and monitors until they met the requirements and never tested the system to see if anything could go wrong. It's now up to the consumer to figure it out each time an electronic system malfunctions. For instance, the "monitor" for the catalytic converter. What exactly is it "monitoring"? If it's the information being supplied by the O2 sensors then why isn't there something telling me that I have a bad O2 sensor? There are no other electronic connections in the converter itself. Also, how does whatever is measuring whatever it is measuring know if the car is in California or some state that does not require the strict "smog" emissions? If all it is measuring is if the monitor reset, then what is it that "resets" the monitor???? If the O2 sensors are measuring the amount of junk that the cat is stopping why aren't OBD2 scanners "California specific"??
With all the frustration caused by "emission monitoring equipment" no one is going to live long enough to be killed from smog!
I think what the industry needs is a group of 14 year olds who can figure a way to hack into the system and clear the monitor. They'd make millions here in CA!! In the mean time the rest of us old farts will have to keep banging our knuckles on engines to figure this out.
I'm at least encouraged by the results of the test I did on the ABS/TCM/ECM coming out as is should as noted in the Jaguar manual, well, except for those lights in the selector. And at this point as long as that issue doesn't give me any trouble codes when I plug in the OBD2 I'm a happy camper. My inferred temp sensor should be here tomorrow so maybe I'll have time to check the temps in front of and after the cats next week.
As far as "old school" cars/trucks go, as long as it was built before 1975 out here in CA I can convert the carb to a fuelie and still not have anything to do with the smog station!! I can build something that puts 500 hp to the rear wheels and drive right past them and wave, LOL. In fact at my last job before finally retiring that's exactly what we did. We didn't have a car in the shop that was newer than '62.
Joe I think you have figured it out. This is not the ghost of Lucas or showing bad Jaguar electronics. What it is showing is buying a car full of junk yard parts. Who knows what was done in addition to what you have found so far?
The O2 sensors are installed in front and behind the catalytic converters. So the system is measuring what the differences are between the two O2 sensors. If they measure the same that tells you the cat is not working. A bad O2 sensor is a completely different problem and that's why the system codes them differently.
But as dibbit posted above keep at it. Your making progress!
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Joe I think you have figured it out. This is not the ghost of Lucas or showing bad Jaguar electronics. What it is showing is buying a car full of junk yard parts. Who knows what was done in addition to what you have found so far?
I hear you Clubairth. At this point I have no idea who did the work on this thing. All I can do is see if I can correct it to the point of passing the smog/OBD2 check. (Mea Culpa about the Lucas/Jaguar comments. Chalk it up to pure frustration)
The O2 sensors are installed in front and behind the catalytic converters. So the system is measuring what the differences are between the two O2 sensors. If they measure the same that tells you the cat is not working. A bad O2 sensor is a completely different problem and that's why the system codes them differently.
I'm going to run the fuel trim checks again next week and see what kinds of numbers I get. I watched a video related to what the fuel trims actually do to the engine and it really broke it down into simple language and charts. I'm also going to do a smoke test to see if there is a vacuum leak that might be causing the car to run lean, although it is running fine, no rough idle, no lag when I hit the gas etc.
But as dibbit posted above keep at it. Your making progress!
On the cats incomplete monitor:
- Is your temperature gauge working fine? (if the engine control unit does not think the engine is getting up to temperature, then that would be an issue - the monitor would not complete)
- Definitely no P0420 or P0430 code - the monitor will not complete if either of these is present or pending
- I obviously assume OK on these, but just reviewing....
How the oxygen sensors evaluate the cats depends on the type of sensor. My understanding (happy to be corrected) for the X100, the upstream sensor is wideband, and the downstream is narrowband (some other cars use narrowband for both upstream and downstream). You can't measure voltage on the wideband, since it is current based, and the only useful measurements come via the ECU, for which you really need to use the Jaguar IDS tool or similar. On the narrowband downstream sensor you can measure the voltage, but in isolation I don't think this will tell you much. I would guess (!) that the ECU checks on the cats by doing a 'oxygen storage' capability test during a period of steady state cruising of the engine. The ECU makes the mixture temporarily rich which removes all the oxygen, then makes the mixture lean which adds oxygen back in, and evaluates how much oxygen the cats 'store' by measuring how long it takes for the downstream sensor to detect the rich to lean transition - the longer it takes the better the cat is working. It only takes a couple of seconds. I don't think there is anyway for you to know when this is happening or how to monitor it.
- any leaks in the exhaust system upstream of the cats will screw up this test by letting in oxygen (but would likely trigger a P0420 or P0430 code).
The test conditions for P0420/P0430 are worth reviewing - I would include this in your next drive cycle.
- Engine up to temperature
- intake air temperature > 18 F and Surface elevation < 8,000 ft (not normally an issue...)
- Varied driving for 3 minutes;
then, constant steady throttle 50 – 60 km/h (30 – 38 mph), 1100 – 1475 rpm > 25 seconds
The fact that there are no P0420/P0430 codes makes it hard for me to consider the cats as the only suspect here, even though they are a candidate :-(
In the mean time the rest of us old farts will have to keep banging our knuckles on engines to figure this out.
