Hi folks

Some help please ! Scratching my head on this one.

I went to start my '97 XK8 from cold the other day but the motor just spun on the starter, it didn't catch. The message centre displayed "ENGINE FAULT".

Pretty sure it isn't flooded as it has always started well and I am careful not to do quick start/stop/starts with it. I did flood it very early on in my ownership of the car (everyone needs to learn !) but whilst it just failed to start that time, it did not display any error messages or DTCs.

I have the AutoEnginuity code reader, but it's not finding any relevant codes. See attached.

I cannot hear the fuel pump going when ignition is in position 2. I have measured voltage at the connector and it is getting nothing. I have measured at the pump's relay base and it is getting 12V on the high- and low-power pins. However it is not getting a negative signal from the ECM.

Bridging the high-power side of the relay base does cause the pump to come on. With the pump forced on, the car still does not start, and still displays "ENGINE FAULT".

- Car has a good battery, full charged and kept topped-up.
- Car is in regular use.
- Fuel tank is 3/4 full
- Keyfob is good with recent batteries
- Brake lights work fine and gearlever solenoid works the way it should
- All fuses are in good order
- I have swapped the fuel-injection and fuel-pump relays with other good ones
- I pulled the ECM to make sure all its connections were good, and that no mice had been chewing the wires. It looks fine and the components eg. capacitors do not show any damage or buns.

Any ideas, folks ?

What constitutes the "ENGINE FAULT" message but with no DTCs ? I guess a failing crank sensor would throw a code ?

Thanks !
Frank

 

You said your battery is kept topped-up, but what is the voltage across the terminals with the ignition in the OFF position?

 

Currently 12.82V, but it was run down a bit with me working on the car earlier

 

Based on the image of the scan, it may be a PATS issue. Is the security lamp blinking, or steadily on?

 

No, there's no security light on and nothing flashing.

Don't know if this is important, but after reconnecting the battery, the "ENGINE FAULT" message is gone. It only appears after the starter has been used for, say 1/4 sec. That's what got me thinking originally that it was the crank position sensor - but that should have thrown a real code, which is hasn't. Engine turns and turns, no stumble, no catch, no misfire. Almost as if it is completely out of fuel - but I guess the inactive fuel pump is the cause of that.

Would a failed security module prevent the fuel pump from activating ? And would you expect to see a DTC or other message for failed security module ?

 

Not sure about the Auto Enginuity code reader software. If you have access to another OBD code reader, see if there are any DTCs that weren't picked up.

I assume you checked earthing points?

 

The AutoEnginuity software can read Jag-specific codes as well the general OBDII codes, it supposed to be quite good. Those are the codes I attached above, they are Jag-specific.

I also have an ELM327 reader which is good for generic codes, but it isn't seeing any codes at all at the moment. It's reading stuff off the car, so is working and connecting, just not finding any codes.

Haven't checked ground points yet, will do so in the morning. There are more than a few !

 

From the looks of it, maybe a key transponder issue? The early UK cars have a transponder, I believe. There is a crypto function built in the security module. The interaction with the key transponder is done with the help of a coil around the key switch. There are a bunch of errors with the steering column. Fuses?

Best of luck, keep us posted.

 

Have you checked the schraeder valve for fuel pressure. Turn the key to the II position and wait 5 seconds turn it off and then depress the schraeder valve. You should get a burst of fuel.
If not then it is possible that the inertia switch has tripped shutting off the fuel pump. Try resetting it.
On the console near the coin holder you should have a red light. Blinks when security is armed and stays constant when security is tripped. Tyr arming the security with the fob and check for the light.

 

I also have AutoEnginuity Proline with the Jaguar enhancement which I purchased when it was first introduced.

Following several software upgrades whch appeared to make things worse, I had lengthy exchanges with AE technical support about its failure to make or maintain consistent connection with first my 2005 XK8 and then my 2007 XK. When it did connect, I was not convinced the results were accurate.

I never got a satisfactory solution from AE. It has gathered dust unused for a few years and I've relied on Jaguar SDD instead.

Graham

 

Have you checked the #7 20A fuse that sits inside the relay on the wiring diagram? Sometimes fuses can blow, but appear to look good. Need to physically pull it out and look.


Have you tried putting a jumper wire in place of fuel pump relay, and see if pump comes on? Jump pins 3 & 5. If it comes on and you have pressure at fuel rail, then pump should be ok.


I have seen on occasion where the ECM does fail inside - on ignition coil circuit, just something to keep in mind. Best to check everything else first and see what results you get.


Also see attachment of code description for Body DTC's

 

Yes, am getting 12V at the fuel pump relay. And when I put a jumper on the base, the pump does run fine (and there is fuel in the rails/schraeder valve). But the car still won't run when the pump is jumped like this. Inertia switch and all fuses are okay.

Something is holding the car from firing, etc, the pump just seems to be part of it.

I took out the SLM security module, it looked fine, nothing burned, no corrosion etc. When locked, the red LED for the alarm is indeed flashing as it should at the gearstick. Doors lock/unlock as normal, alarm chirps when locking etc.

So that maybe leaves the key transponder, right enough. I tried my spare key with the car but no joy, the engine cranks but does not start.

Two codes on the SLM are U1135 (ignition switch/starter) and U1041 (vehicle speed). But the U1135 would be interesting since it is showing up for the driver's door module as well as the driver's seat module --> something to do with the coil in the ignition-lock area that reads the transponder within the key ?

 

I realize this is not the preferred way of doing things, but you might want to consider resetting all the codes, and then check which ones come back. Unfortunately, these codes are not date-stamped, so there is no way to know how old they are. Hopefully, after a reset, the true code will show and point you in the right direction.

You might want to check the wiring diagram and figure out if there is a fuse somewhere for that transponder coil. From memory, issues have been reported with that coil before. Someone complained of erratic starts, sometimes getting stuck places, and needing a tow. It was eventually diagnosed to be a bad security coil, I believe. I am not aware of failed key transponders, FWIW, and you have pretty much eliminated that possibility by trying a second key.

Best of luck, keep us posted.

 

Always take it from the horse's mouth:

X103_U_DTC.pdf

U2012:

Key transponder module message corrupt

KTM to BPM data circuit: open circuit, short circuit to B+ voltage,
short circuit to ground, high resistance
Key transponder module failure

 

Thank you sir, that is a brilliant document, I hadn't seen it before.

I have reset the codes, but U1135 and U0141 keep coming back - not just at the SLM but for the door and seat controllers. There are also some recurring BPM codes to do with the steering column reach/rake, etc --> so I will search around the steering column for damaged cable or earth points. There are no issues with the wiper/indicators/etc there, so it might be a red herring.

U1135 sounds like the likely culprit (SCP (J1850) Invalid or missing data for ignition switch/starter).

I removed this from around the ignition barrel to try to ID a part number, but it's blank. There is no resistance or continuity across the two wires in its connector. If it is a coil, I would have expected something.

As much as I hate throwing parts at a problem, I might order one up in the morning whilst I do some more checking of cables and connectors behind the steering wheel.

 

There is a separate key control module. I believe the error code points to the module itself. It's all here: jagxk1997.pdf

 

Scratch that, a better check confirms that there is 33.4 Ohms across the coil, so tomorrow I will dig out the transponder module and see how it looks. Think it's somewhere near the fusebox on the passenger side

 

Hey lads

Where exactly is the KTM (Key Transponder Module) on my 1997 XK8 ? The diagram in the electrical manual says "adjacent to the fuse box" on the passenger side, but I just can't see it. I have the glovebox and the kickpanel removed.

I have a spare KTM ready to go in but I still need to get at the connector to measure resistance/volts/earth in case the replacement doesn't solve things.

Thanks !

 

You may want to have a look on the driver's side as well if you haven't already done so. You may be also able to recognise the module by following the wires.

 

Thanks for the suggestion.

That's where it appears to be ! That's not what the electrical diagram says, but I think I see it hiding behind the air vent. I removed the knee bolster and the dash gauges as well as the vent, but it looks like it can be got to via the vent alone. No idea how I will get to the rear screw though, it's under the not-very-flexible plastic pipe.

Ran out of time tonight, I'll play with it in a day or two. Thanks again !