Hello all. Thank you for reading this. I have a 2003 XJ Sport with 2 different intermittent starting problems. Not sure if they are related or not, but I thought I would mention both anyway.

The first is a no crank. No rhyme or reason to it, every once in a while, it just doesn't crank. Within about 10 minutes of trying it, it will eventually turn over. Sometimes when turning the key, it hesitates to start for a fraction of a second. When I have tried most suggestions on this forum. What's left to check is the transponder ring. I'll check that soon.

The BIGGER no start issue is a crank, no start. It seems to happen every time I drive for more than 15 minutes. If I go to a store and come back out, it just cranks and cranks. If I wait about 3 hours or so, it starts right back up like there's no problem. I say that it's intermittent, but now it happens almost every time the car heats up.

I've checked the fuel pressure at the rail, and it's a constant 42 PSI. The ignition relay is providing adequate power to the ignition system, however the ECM is not sending any pulse signal to the coils. The crank sensor impedance fluctuates, but seems to be within a good range (1.012 - 1.3). The ECM relay is getting power, but that's as far as I've checked.

At this point I feel like I'm not sure of what to check next.

Thanks again for any suggestions and all of your help!

 

The ECM relay is getting power but is the relay sending power to the ECM??
Is the ECM relay/fusebox connection OK??
Are there any DTCs in the ECM??

If you have a diagnostic code reader that has data reading capability then you can watch for things like Mass Airflow and Ignition timing and coolant temp etc.
If the ECM is 'alive' during cranking, you should see some readings.

more diagnostics!!!! let us know what else you find!!

bob gauff

 

Hey Bob, Thanks for your reply.

It was unclear to me where the power from the relay goes into the ECM. I'll check the relay/fusebox connection in the AM.

There are no codes coming up at all and unfortunately my code reader doesn't support data reading.

 

Just heated the car up and duplicated the no start. The ECM connection at the fusebox appears to be OK.

The ECM has power to it while cranking.

Is it possible that the ECM is overheating due to the heater being on inside the cabin? The ECM feel pretty warm to me. It appears that there is an open hole going into the cabin from the ECM compartment. Should this be covered or is it supposed to remain open?

Todd

 

It seems that the heater isn't affecting the ECM. Tried another test run with the heater off and the ECM outside of it's compartment. No change to the no start condition.

 

When I worked at the dealer years ago I had a car that had faults like you describe. I could not duplicate the faults on a regular basis so we called a Jaguar FSE (field service engineer). We tested and drove the car for all kinds of simulations and finally the FSE laid his hand on the ECM during a WDS data download and said that the ECM was WAY TOO HOT!!!!!!!!!!!!!!!!

He called Jaguar Tech Line and talked to several people about part numbers etc. and told me to replace the ECM.

The new part fixed the problems!!!!!!!

The external heat will not cause the ECM to overheat but the ECM might be faulty and getting TOO HOT.

Just something I remembered from years ago. Might not be related but....

bob gauff

 

Thanks Bob!

Are there any sensors that you can think of that may be causing this? At this point I'm just going through everything I can!

Todd

 

If the ECM is overheating or operating too hot, I don't think an input sensor will cause it.
Possibly a heatsink fault for a component inside the case or some 'controlled' component drawing too much current??

I don't know, you will have to make the determination if heat is the cause!!

bob gauff

 

Isn't there a cooling fan for the ECM?

 

The cooling fan is for the entire control module box. The box contains the ECM and TCM.

bob gauff

 

The only time i felt the ECM really warm was when I pulled it out of the control module box. Since then, I left the box open and the ECM out the wither air (40 degrees). Again after getting the car warmed up for 1/2 hour, it still won't start. Feeling the ECM at that point it wasn't warm at all.

 

Anyone have any ideas?

 

Still working on this problem. Found out something new today. Started the car for about 5 seconds, now the same crank, no start condition is there. Soooo apparently it doesn't need to be warmed up for this to happen. I'm starting to wonder about the crank position sensor. The impedance seems to fluctuate from about 1.12-3.

I also checked the ECM for any signs of cracked solder joints. Nothing the I can see.