On my recently acquired 1997 X-308 Daimler LWB (aka Jag VDP), she's recently throwing "Gearbox Fault P1797" yellow warning light during city start stop driving which clears upon an engine restart; on freeway driving, she hasn't so far thrown an P1979.

Gents, with your esteemed knowledge of the X-308, is the A-Drum acting up or is it the ABS module power-connection acting up?

Please advise how to further diagnose this condition. TIA.

 

P1797 is a CAN circuit failure between the ECM and TCM and the transmission defaults to 4TH gear.
My first choice would be to check the connector coming out of the transmission going to the TCM. The seals are known to go bad and flood the connector with fluid.
Next I would examine all of the wires coming from the transmission for any damage, chafing or breaks.
Finally I would remove the TCM plug and clean the connector points with contact cleaner and do the same for the ECM.
A drum failure not likely the problem and the fault is not related to the ABS.

 

+1

 

I'm pleased to report P1797 has not recurred once in the last two days of driving.

Now I realized the period when I experienced intermittent P1797 faults was several days in-a-row of extremely heavy rain, and the transmission signal harness/connector may have moisture contamination due to weak/failed gasket/O-ring(s). Next time when the X-308 is on lifts, I will verify the condition of those parts and report my findings.

Thank you so many guys for putting my mind at ease regarding major repairs.