New user to this excellent forum.

I have a 2000 XKR. Love it when it runs correctly. However, now when I start the engine I get the engine light on and the message "Restricted Performance".

Codes present are:

P1642 - CAN Circuit Malfunction
P1797 - CAN TCM/ECM Circuit Malfunction
P1000 - On Board Diagnostic System Readiness Test Not Complete

After a few minutes I get the messages:

"Failsafe Engine Mode"
"TRAC Not Available"
"ASC Not Available"

Where do I start? Do I have a general electrical problem?

Any assistance or advice would be much appreciated.

 

First of all, as always; Buy a new battery!
Then check and clean the connectors to the ECM and TCM. It is located under the hood at the right just below the windscreen under a plastic cover by the hood lock.

 

+1

A partially discharged or failing battery IS the number one cause of weird electrical issues on a Jaguar.

Graham

 

Thank you for your assistance and advice.

A new battery did not fix the problem. After a few minutes the symptoms were exactly the same.

I will look at checking and cleaning the connectors to the ECM and TCM next.

 

Check the wiring looms and connections on the gearbox for damage.

 

P1000 is not an issue, just a readiness code which will be P1111 when all is good. CAN 1642 is generally a wiring issue in the CAN bus or a module fault. Have you fixed the ABS wiring issue yet?


P1642

P1797 says the TCM cannot talk to the ECM.


P1797

So, the first place to look, as suggested above is the wiring between the TCM and ECM, look for a short (bare wires, etc). You can look at the resistance across the whole CAN bus using the diagnostic port connector (OBDII connector) and a multimeter. Resistance between pins 6 and pin 14 should be 60 ohms. If it's near zero, there's a short somewhere. If it's 120 ohms, there is an open circuit between the OBDII connector and the ABS module. If there is a short, and if it is between the TCM and ECM, you can confirm this by first removing the TCM connector. You should still have a short across pins 6 and 14. If you then remove the ECM connector and there is now 120 ohms, the short is in the wiring between ECM and TCM.


OBDII Connector

 

Throttle body may need rebuilt.

 

I’d look at the ABS module, traction control will trigger reduced engine performance I believe, and when a module becomes intermittent it can tank the canbus link. It’s involved in vehicle speed, which both the TCM and ECM need to know to function correctly. Traction control is also involved in what gear your TCM chooses, how much advance the ecm uses etc.

 

UPDATE

So as suggested here I tried a new battery and when that did not work I returned the battery. However, I did not re-install my old battery for a couple of weeks. When I put the old battery back in after sitting a couple of weeks the engine light was on and the car was in restricted mode, but not emergency mode. I was able to drive it around the block fine. I put the diagnostic scanner tool on it and it went into emergency mode again, so I shut it down.

The next day I started it up and the engine light was on, but it was not in restricted mode. I drove it quite a bit as it never went into restricted mode. I was afraid to put the scanner tool on it to check the engine light.

The next day I went to drive it again the engine light was not even on. It apparently has fixed itself. It has been running great the last few days with no engine light on.

Every day that I tried it it seemed to get one step better. Strange (to me at least) but true story.

 

Was the SERVICE ACTION S484 performed on YOUR CAR?