Disco 2 limp mode + p1562

[Gillarc]

Been chasing an electrical ghost for longer than I care to admit. Hoping someone has a last chance Hail Mary solution. P1562 code throwing me into limp mode. Replaced so far: battery, alternator, grounds, XYZ switch, ECU, TCU, tried overlay wires everywhere. Limp mode only occurs at 35+ MPH and at deceleration/down shifts. At the point where I’m about to try swapping trans, replace engine and trans wire harnesses or just give up entirely. Hoping someone has seen it before.
thanks

 

[Flyfish]

Have you checked the voltage while it’s running to see if it’s actually low? Is the serpentine belt routed correctly? And maybe verify your cats are good.

 

[HIDave]

Check the engine plug wires. Mine had one that was arching. Would make all things a mess, including the occasional limp mode, till it was replaced.

 

[JUKE179r]

From the RAVE:
P1562 - Battery supply below 9V while engine running

Since you have a slew of new parts, recheck your battery connection cables are tight and not loose or corroded.

Got SAI?

 

[Gillarc]

Thanks for the responses: yes, I’ve checked voltage live and it never actually drops. Belt is correct, but haven’t checked cats or plug wires. Battery cables and connections are good. Yes, I have SAI. Could the pump cause it?

 

[Flyfish]

Since code P1562 is listed under gearbox faults, did you check the vss and similar items and their connectors/wiring?

 

[Gillarc]

Will do. Thanks Flyfish. Is there a VSS module? I thought the D2 used the SLABS for that? Or do you mean the one inside the trans?

 

[Flyfish]

Correct and it’s just inside the pan. I can’t say if that’s your problem. Just to check the connector/wiring and/or voltage for the #3 Gear position switch connector and #4 Solenoid valve/speed sensor connector on the autobox and under the driver seat to the EAT Ecu. You may be able to pinpoint if a particular wire has bad voltage. Chapter 44 in the workshop manual should help knowing which wires to check.

 

[JUKE179r]

I 've never dealt with any D2 transmission issues but would it help to use a diagnostic tester to clear the fault codes and reset adaptive values for the gearbox?