Hi there,

I'm trying to figure out when my 98 (late 97 built) XJ8 will show the check engine light and save a fault code.

For example:
When I pull the plug from the MAF, the engine just stalls. Red light (in speedo) and it says 'Motor Aus' (engine off/stall). But no check engine light.
When I start the car with the MAF plug removed, it stumbles and coughs (obviously) and says 'Motorleistung Eingeschränkt' (restricted performance). Yellos light in speedo is on but no check engine light.

When I start the old bugger, the check engine light illuminates and then turns off as it should... BUT the same can be done with a defeat device... The people who sold me the car, were a little 'lieing'. According to them it is a 4.0l... I didn't buy the car for a 4.0l I bought it as I wanted it... It wouldn't surprise me, if they fitted one. Especially since I can't enter the car system wkth Jaguar SSD. Only IDS or what ever... Or is that normal for a 97/98?

Cheers

Damien

 

I am not 100% sure what you are after (Germans and their English ~~ joking~~).

Are you looking for a way to force the check engine light on, and create a code?
Then pull the connector from the coolant temperature sensor in front of the thermostat.
Should give engine warning (restricted performance), code P0117 (engine coolant temperature circuit low input) and light the CEL.

 

Don't pull the modules. You will short out the ECU if you do.. That would create a CEL, but an expensive one.. Be careful what you ask for in a 19+ year old KAT.
As stated, disconnect the coolent sensor at the thermo housing.

Also, I this you might be overthinking this. Very few people know how to reprogram the ECU to ignore a CEL code.

If you have an OBD II meter, it should show if everything is operating normally. It should also tell you if the car is ready for emissions testing.

Also, when you get your emission tag, that will tell you if any defeat was installed as it won't pass if there is.

 

I think if the SDD version is higher than a certain number it won't connect to our old x308's. I haven't used it before though, so don't take my word for it.

Quickly looking thru JTIS there's a section, electronic engine controls, with a pretty detailed description and operation on the electronics, with circuit diagrams and associated fault codes and all. That would be a good place to start if you really want to get into the guts of it, along with the CAN guides at the end of the electrical guide. I don't remember if there's a table covering all the things that will trigger a CEL, but I've seen some pretty thorough ones while digging around the service manual.

 

Daim,


I'm reasonably sure Jaguar Forums doesn't have prizes.


But if they did you would be in line to get one, as owner of possibly the ONLY X308 on earth that CANNOT get a fault code!


Congratulations!!!

 

Cheers people!

The reason is really simple: I need to see if someone has played around with the CEL. Yonks ago, my old Volvo 960 had one fitted. It was basically not programmed into the ECU but more so the light was disconnected from the car's ECU system and it ran a simple timer. The result was, every start all the lights lit up and then, once a certain period had passed, turned off. So it was a delay switch.

I really have trouble trying to get that light to work. Not that I want a fault code but I want the car to work properly and it doesn't really want to at the moment... And it isn't saving any codes nor is it showing any lights.

I have a new TB sitting here to install later on (want to do it tomorrow when everything else arrives to do a full service - 5000 km already overdue... ) and I assume it really has something to do with that...

I'll try unplugging the coolant sensor at the thermostat tower...

What makes me wonder a lot more is, that, even though the lambda sonds are working perfectly, the ECU has a "long term adaption" or -15% (so it is running rather rich). See:

 

I have to go down to check, but I am rather sure that if I turn my key to pos.II, but don't start the engine, all check lights stay on forever.
I don't really see how they should circumvent that with a delay switch.

 

It is possible... People do that if they want to sell a car with a faulty system...

Criminal energy is one of the worst possible. Every 2nd car here has it's odometer turned back/tweaked. Mine luckily wasn't (you can tell that by looking at the condition of the car). But my old C30 was turned back by 100.000 km (!!!)...

 

About the only way is to connect the MIL (its proper name) to another lamp (the airbag or ABS or whatever) that self-tests at ignition on, the way the MIL does.

Forget any cunning reprogramming on these cars - way too hard and costly so you do not want to be thinking about it.

Bear in mind that some ways to force a code will (by law) need two engine warm ups to put the MIL on (but would be seen as pending codes sooner).