Good Morning Folks
I'm in a bit of a vicious circle. Sent my ECU from my 2003 /2004 X350 XJR Away to be tested which came up OK seemingly although programming needed to be rebuilt. Received back and installed and now car won't start. (It was previously starting but with a rough idle - now, I turn the key to the starter position an absolutely nothing) The same messages that provoked the test in the first place are still coming up on ignition 1 and 2, I.e.: DSC not available, Gearbox Fault, Parking Brake Fault, Air suspension fault. Etc etc. However , now because I can't start the car, the Foxwell OBD scanner won't communicate with the car. I had previously noticed that with scanners in the OBD port, they would not communicate either on ignition 1 or Ignition 2 and would do so only when the engine is actually running. The scanners instructions seem to suggest that with ignition on only, they should communicate with the car. Is this correct or do all X350s need the engine running to communicate with the port. If this is the case I'm well and truly scuppered. Can't start the car and can't interrogate the codes to find out why. I have checked the battery and the front grounds all ok. Scratching my head!

Any Help or thoughts would be much appreciated! I've gone through the fuse boxes and all seem good.

 

Scanners will communicate with the ignition on and engine not running. Nothing peculiar about Jaguar there.

Did you do the work or someone else and have you checked all connections?

Is the battery good?

 

Thank you for your response
Battery showing 12.9 volts so should be ok
Connections work with engine running and I can retrieve Jaguar specific codes from all systems and modules including also standard OBD codes but switch the engine off and Hey Presto! Lost connection on all modules. Bizarre! Now that the engine won't start stuck! Codes previously thrown up with engine running and prior to sending the ECU away included
P1637, 1642,1646,1260,1582 and the old chestnut P1000. Module codes previously identified include B2496, 2363, 2598, 2262

 

This is a long shot but it could be something to do with security.

Try locking and un-locking the car with the key fob a few times.

 

Thank you for the prompt. Tried it a few times but seemingly no change with the scanner. Still no connection. Maybe I'll try with the mongoose tomorrow and if that fails, perhaps check the obd2 pins although I'll have to find out what pin should read what with the test meter.

 

The pinout of the OBDII Data Link Connector (DLC) is in the Electrical Guide, which you can download here:

2004 Jaguar X350 Electrical Guide

Have you discussed the no-start condition with the firm that reprogrammed the ECM? Perhaps they will have some ideas.

When you reinstalled the ECM, did you tighten the 5-lobe tamper-proof Torx screw securely? If not, the pins in the connector may not be connecting.

Cheers,

Don

 

Thanks Gentlemen.
That was a really good call Don. I tightened up the Torx security bit a few more turns and Hey Presto a running engine. Thanks a lot. I've still got all the other issues and now a gearbox fault showing which now won't let me take it out of Park also fuel monitor high and overload messages to add to all the others but it least the engine runs. Back to the drawing board and the other issues. The foxwell scanner won't communicate with the up and downstream sensors on bank one so that might be yet another issue because I was showing an Upstream o2 sensor shorting or open on bank one before. I'll keep you guys posted on developments but thanks again for your valued assistance. You are gems.

 

Just a short update. Due to Don Bs brilliant insight I now have a running ( but badly) engine. I can also communicate with some of the modules at Ignition 2. The messages and codes I am getting are
P1000
P1637 Can link ECM/ABSCM Circuit malfunction
P1642 Fuel pump monitor circuit High Input
P1646 Auxiliary Inputs / Outputs
P0603 Internal Control Module Keep alive memory (KAM) Error
Jag specific codes are
U2520 Missing Message from Instrument cluster
U2516 Air suspension module bus off
U2521 Missing message from ABS
U2523 CAN message timeout from ECM.

Can anyone tell me if these codes indicate loom or connection issues, alternatively a bad ABS module. I have cleaned and reseated the ABS connection with no improvement, rebuilt the 3 grounding points behind the headlights and checked battery voltage (12.90 Volts) and also of course the ECU connection. The ECU itself was found to be good by the ECU test and repair company. Thanks for being patient with me guys! I really have never delved into the electronic side of these cars before. Sign of the times though!

 

Hi runcoach 100,

It is likely that at least some of those diagnostic trouble codes (DTCs) are spurious and due to the ECM having not been fully connected. It would be worth trying a "hard reset" to see if some of them go away. To do so, disconnect the negative battery cable and touch its terminal to the positive battery terminal. You don't have to disconnect the positive cable - the battery will be out of the circuit. Opinions vary on how long to hold the battery cable terminals together, but I generally count to two minutes or so. This procedure drains the capacitors that maintain power for the keep alive memory circuits and resets the systems to the factory default settings. It also clears some of the DTCs.

Another thought: your static battery voltage is high, so it has a surface charge. To remove the surface charge, turn the key to position II (ON) without starting the engine, and turn the headlamps on for one minute. Turn off the headlamps and turn the key to the OFF position and remove it from the ignition lock. Now measure the voltage across the battery terminals.

Another worthwhile test is to measure the voltage across the battery terminals while cranking the engine to start. If the voltage sags much below 11V, that may be triggering some of the DTCs. Note that many voltmeters cannot react quickly enough to give a true indication of voltage sag, so the reading you see will probably be high.

Please keep us informed.

Cheers,

Don