On a 1997 xj6 I have a check engine lite but don't have any codes show up and I can reset it to make the light go away.
Has anyone else has this problem?

 

I'm assuming you mean you can't reset it? If so then you most probably have a short to ground on the wire from the ECM to the instrument pack.

 

No, I think he is saying he makes the light go away by resetting. I suspect that a non OBD code may be causing the light, but the OBD scanner will not read it. I thought that even if, say the transmission were to throw a non OBD code, you would get a general P series fault that said something like "Transmission Error".

I would try to get the code read by someone with the dealer level software to see if it reads a code. Either the WDS, IDS, the newer IDD or AutoEnginuity should read theoretically something if the light is on.

 

Hmmm, could be Ross but that sounds counterintuitive to me. There are a number of transmission P codes that do not cause the MIL to illuminate, such as 1780, 1781, 1782 etc. But I would not have thought the opposite was true? I always thought that the point of OBD-II and MIL was to provide a standardized way the communicate problems? I can understand proprietary software being needed to calibrate or set up a function or operating parameter but would not have thought it necessary to determine the initial area of concern for the MIL? Would be good to know though

 

Yes I cant reset it. It's happened a few times in the past but after about 1000 miles it goes away. This time though it's been about 3000 miles and it still has not gone away and no codes show up so my reader can't reset it

 

Hi AlbBolivar,

I don't know if this is true on an X300, but on an XJ40 a weak battery and/or corroded ground points or battery power connections can illuminate the MIL and store a FAIL code in the computer with no number to point to the actual source of the fault. How old is your battery, and how long has it been since you cleaned all the battery power connections and grounds in the car? Have you had any hard-starting issues?

Cheers,

Don

 

Ross and Allan,

Just to add some confusion to the issue, here's a rambling hijack of AlbBolivar's thread:

From reading a brief history of the development of the Lucas SAGEM GEMS Engine Management System used in the X300, the system was nearly "fully CARB OBDII compliant" in 1995 except for one minor issue (regarding its handling of backfires, I think, which was resolved). By law, all cars sold in the U.S. beginning in 1996 had to be fully-compliant, but if I understand correctly, the OBDII standard only applies to emissions-related malfunctions.

However, OBDII is an "extensible standard," which means it may be extended either by the sanctioning body, CARB (the California Air Resources Board), or by individual auto manufacturers who choose to use the OBDII port for diagnosing faults other than those related to emissions.

A slight digression: the Jaguar XJ40 was OBDI, with a means of displaying fault codes on the dash via the VCM, or Vehicle Condition Monitor. The early cars had a catalog of only 8 codes, the later cars 24, all emissions related. There was also a proprietary electrical connector for interrogation by the Jaguar dealer diagnostic system (the connector looks nothing like an OBDII connector).

By the time Jaguar got to the X350, all diagnostic functions were handled via the OBDII CAN port, and the catalog of codes includes not only generic emissions faults but a full range of what appears to be hundreds of Powertrain, Body, Chassis and Network (U) codes, many of which are Jaguar-specific. My better-than-average Innova Equus 3130 OBDII scanner can read the emissions-related codes from our X350 and the famous P1111, but it couldn't read several B, C and U codes that had been stored in our car. For that, I had to use the dealer-level JLR SDD (Jaguar-Land Rover Systems Driven Diagnostics) computer-based system.

All that to say, I haven't counted all the X300 codes (there are a lot of them), but they also appear to be mostly emissions related (a few, such as the Park-Neutral Switch errors P1514-P1517, may not be). There are a number of codes that are common to the ECM and TCM (such as P0605, P1775-P1777, etc.). I don't have a reference that lists the transmission-only codes that Allan referenced. The '96-'97 cars may have more codes than the '95s but I'm not sure.

So here are some other questions I do not know the answers to:

1. Are there codes in the X300 system that cannot be read by a generic OBDII scanner and require a Jaguar dealer-level tool?

2. Does the X300 have a means of displaying codes on the dash like the XJ40 does? For some reason I think I've read on this forum a description of how to access codes via the dash. If so, will the dash reveal codes that do not illuminate the MIL?

I'm looking forward to being educated.

Cheers,

Don

 

I'm certainly no authority on the matter, but I can answer #1: Yes (C1095, for example) basically, P-codes are all you get from the X300 with a generic OBDII reader - and I've read somewhere that even though Auto-Enginuity with Jag pack will read the other codes and generally mess around with settings like you can do with WDS - It may not work on MY1995's. I believe X308 is quite similar in that it has C, B and what have you but only lifts its skirt on P-codes for generic readers

#2 - I haven't found it if so. It will give you radio codes on the radio and you can interrogate the HVAC system for codes for it. You may be remembering reading about the S-type - you can put it's instrument panel into "Engineering Mode" or some such and read lots of data, some codes, but I'm not sure they cross to the same as you'd read with the OBDII.

 

Don,

Yes, just as AlHobro1 states, there are many codes that are generated by various system controllers. The examples I gave were a few that related to the TCM, there are several more. You can see the full list of codes by downloading the Electrical diagnostic manual covers 1 & 3 (cover 2 if you're interested in the V12)

But my point was that these faults do not (or are not supposed to) illuminate the MIL. The manual specifically details which codes will and will not set the MIL. So it would appear that you can have a fault code without the Mil illuminated but I cannot see the opposite occurring. Which of course is the issue that the OP is facing.

There is no VCM facility on the X300 as there is on the XJ40 or the trip computer equipped XJS models from 92-94. Though the A/C control panel can be interrogated to reveal climate control issues and the radio will inform of certain problems but that's it.

I also own an Innova 3130 and can read only P codes (when the ECM is bothered to set them )

 

Allan,

Thanks for the additional info. As I mentioned in a previous post, on the XJ40 the MIL will illuminate if the car fails to start due to battery voltage that falls to between 10-11V while cranking. The engine may rotate, but the ECM will not trigger the ignition to fire. The VCM shows the word FAIL, but gives no fault code. Typically this code can be cleared, but it will be re-triggered if the low battery voltage is not corrected and the engine does not start successfully. I'm still wondering if low battery voltage and/or corrosion on ground points and/or battery power connections could be contributing to AlbBolivar's MIL. So far, your short idea and the possibility of battery voltage/charging/ground corrosion issues are the areas I would suggest AlbBolivar investigate and report back.

Cheers,

Don

 

Don,

It seems as though the OP does not have any issues with the car starting or running, just that the MIL is on and can't be reset? There's almost no chance that the X300 will start and run properly with low battery voltage but who knows?

 

The "who knows" is why I'm suggesting the OP rule out low battery voltage and/or corroded grounds & battery power connections. They're known to cause hard-to-diagnose electrical gremlins, so why not check them in the absence of more substantive clues?

 

Thanks for all the replies guys. Seems like a short or battery is the first things I should check for. Will try that first thing tomorrow morning and see if that works. Will report back with results after 24-48 hours if check engine light stays or goes away

 

Don,

I don't disagree with you at all, I was just trying to understand the OP's situation. I wasn't clear if he had starting issues or running issues or not.

My thought process was based on he had a CEL that would not turn off, could not be reset and had no apparent fault codes. And since he had no apparent issues with starting or running the car and that the CEL is illuminated by the ECM switching a 12v signal to ground, it seemed to me that a short to ground of the wire to the CEL would be a logical thing to suspect.

Never hurts to check the basics first though

 

That's a good point, Allan, which leads to the thought that perhaps the battery voltage is okay, but if the problem isn't with a short to ground as you've posited, it could still be due to low voltage in some circuit other than those for the starter & ECM due to high resistance at one or more ground points, a fuse box power connection, fuse box circuit board, etc.

Cleaning all the battery power connections and grounds, and resoldering cold solder joints in all the fuse boxes made our XJ40 much more reliable and improved hard starting that we'd lived with for years. Series resistances are cumulative, so that's why I tend to recommend cleaning connections when these sorts of otherwise inexplicable gremlins pop up.

Cheers,

Don

 

Thanks Don for the info on your XJ40. I have been having hard start issues with my 94 Daimler lately. I only drive it once or twice a week and it has gradually become harder to start...cranks three or four times before starting and chuffs when the key is released. Have read the previous post about the XJ40 having fuel pump faults and have just started to go through the diagnosing process. The vehicle seemed to crank ok before but after a good charge and a new set of plugs it has been starting ok. Will let the car sit for a week and see how we go. In the meantime I will go through and check all grounds etc. Amazing what a slightly low OCV can do.


Cheers


Hamish

 

Hey guys, the CEL issue is still around. A few weeks ago I had an igntion coil fail on me and due to the misfire the light would flash indication a major problem. I fixed the coil issue and was hoping that after resetting the P code that it would reset the whole system but still didn't fix the original issue. CEL is no longer flashing but it still stays on with no codes showing up

 

In my experience, the IDS does pretty good with my mid year MY 95 TCM, BPM, and ECM modules and codes. It, and AutoEnginuity both show transmission speed va;ues, solenoid actuaation, seat and security switch stastus, ABS faults and status and so on. the list for AutoEnginuity is on their website and it all worked as promised in my experience. And the MY 96 ECM I replaced the original with apparently workjed the same as the MY 95.

I do not know the rigorous definition of how it works, but in general, there is an OBD general fault that indicates some other faullt exists in the TCM, but you have to interrogatge the TCM to find the specific fault.

I do not know of any OBD fault that does not light the CEL. Allen, can you enlighten me?

 

Hey guys, I think I've finally got a fix for this problem but not really sure what would cause it.

What I did was,
I swapped ECU's between my 97 XJR6 and the 97 XJ6L.
The 97 XJ6L ecu in the XJR6 showed a CEL right away and I was able to view 4 trouble codes. Which were all misfire codes so I just reset all the codes. I had a coil go bad a few weeks ago which is the reason those codes came up but fixed right away and the CEL stayed.
It seems that the codes get stuck in memory and basic ODB II scanners can't see them (I didn't try any advanced dealer scanners)
But anyways, after I reset the CEL for the XJ6L ecu when it was in the XJR6 I put it back into the XJ6L and so far no CEL showing. I've started the car up 3 times and let it idle for about 3 minutes or so and still no light. I still have to test drive the car around to make sure this is a "fix" but so far so good for everything.

Also, with this experience, XJR6 ECU isn't interchangeable with N/A cars. I had a sporadic idle in the XJ6L when installed but the XJ6L ecu in the XJR6, the car seemed to idle fine. I didn't test drive it because I wasn't sure what the effects would be.

Anyways, if you have this problem and another x300 ecu (possibly the same year) this would be a "fix" for it just to get the CEL to go away.