Not your traditional "No Bus" P1694 issue - engine actually starts

Ok, here's the issue (and I've searched for anything similar)

2000 XJ - new OEM CPS as of last week didn't resolve the P1694 "No Bus" issue.

Symptoms - laborious start first thing in the morning - happening over the last 3 weeks. Outside temps in the 60s-70s. Engine DOES start. Idles slightly rough very briefly then evens out just fine. Fuel pump is engaging.

"Torque" app showing P1694.

All gauges on dash work without error.

Battery and all body grounds inside and out have been checked/cleaned.

Guessing it's time to do the reference voltage check on all of the 5v sensors.

Any other thoughts?

Thanks.

Scott

TCM, NSS, or a wiring issue.


P1694 Fault In Companion Module. No CCD/J1850 bus messages received at the power train control module (PCM) from the AisinWarner Transmission Control Module (TCM).

P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.

Possible Causes
-CCD Bus (-) circuit open between PCM and TCM.
-CCD Bus (+) circuit open between PCM and TCM.
-Transmission CCD bus wiring damaged.
-Faulty TCM

Tim,

Possible to be NSS and still start?

Thanks.

Just an idea which may or may not be your issue, bad cell in the battery. At start the marginal battery pretty much tanks and it takes a few moments for the alternator to stabilize the voltage. Low voltage is liable to cause all sorts of issues.

Load test the battery and you can eliminate it as a possible cause. Voltage may or may not be an indication of a bad cell, the remaining good cells will try to compensate.

I would focus on the OBD-II trouble code Possible Causes first. The NSS could potentially be damaged, or partially failed, and be outputting faulty readings while in Drive.

It was all wiring. Don't think I had a single sensor that didn't have at least one melt through/frayed. All repaired with the help of a friend and running like she means business. Thanks for the heads up on where to look.

zeke2230 said:

It was all wiring. Don't think I had a single sensor that didn't have at least one melt through/frayed. All repaired with the help of a friend and running like she means business. Thanks for the heads up on where to look.

Click to expand...

Which wires ?

O2 sensor connectors, IAT, IAC, TPS, MAP, Coolant temp, injectors... All of them had varying degrees of decay leading to voltage loss, which led to the dreaded P1694...