Intermittent stall, with and without restart possible

DOUGSY

MEMBER
2006 JAGUAR XK8
4.2L
V8
2WD
AUTOMATIC
61,000 MILES

Okay, I have looked for two days for at least a picture of the back of the connector to the TCM on my vehicle.
After troubleshooting the faults P1637 and P1643, I have found that the problem may have to do with CAN faults between the ECM and TCM. Under the car, there is no back, or shell, to the connector to the TCM, set at the back RH side of the transmission. The pins and wires at the back of the connector are therefore exposed to the weather (and winter salt water, etc.). The car has been extensively detailed, including under the car, so I expect that cleaning fluid has been applied to the connector as well.

This car has 61,000 miles on it, and looks like it is still sitting on the showroom floor -- yes, even underneath.
VIN is SAJDA42C062A46202.

The problem is intermittent, and the car runs beautifully, until it doesn't. Then it shuts off, and we go to the side of the road. Ignition off, then re-start, and all is okay. One other case is that twice I have returned to the warm car after it has been sitting for a while, and it won't start. Only after sitting and retrying for 10 or 15 minutes does it fire right up, asking "yes, what's your problem"? It has once, after the above scenario, started in performance is limited mode. Took it home right away, then turned it off and restarted. It was ready to go, and seemed unable to understand why I am concerned. Runs like brand new, again.

1 Reply

AL514

MECHANIC
4,118 POSTS

Hello, sorry to hear about your issue, intermittent issues are one of the toughest to diagnose, especially communications networks. Do you have a scan tool and/or lab scope? You can look at the voltage readings for CAN high and low, but it's better to look at the signal. If you think the connector for the TCM has corrosion, unplug it and inspect both sides. The diagnostic procedure for finding a bad module is to monitor both signals and unplug modules one at a time until the signal returns to normal. But turn the key off before plugging things back in. Both those codes seem to be network related, so hopefully we're chasing the right issue. *Edit. You can access the CAN network at the obd2 connector, it's pin 14 and 6. You'll have to back probe the connector, never jam over sized pins in any connectors. Here's a diagram of the obd2 connector.

Image (Click to make bigger)