Gearbox Fault - missing engine RPM signal

[zzsteve]

Hi to all,

Working through issues on the '95 HSE and still have occasional engine stalling, not always under load. Message centre says GEARBOX FAULT and when I Nanocom the ECM there are no faults logged and on the gearbox I find " missing engine RPM signal".
CPS comes to mind, so I have looked at the output and it is a healthy >10V swing with no glitches. Camshaft sensor signal also looks clean. Fuel pressure passes the crude spray test, but I haven't put a gauge on it yet. Battery voltage is steady 13.9.
As I understand it now, 'missing engine RPM' just means the engine stopped - for whatever reason. There is no CPS signal path to the gearbox module.
Any ideas on where to go next?
TIA
Steve

[PeterH]

CPS failure will stop the car dead, it happened to me not long ago, not pretty!
I get gearbox fault errors when I have dirty battery terminals, or a low battery.
If it was me, first thing I would do is clean the battery terminals and make sure the clamps are tight, then get a proper load test done on the battery.
Is it 13.9 volts while running? What is it at rest?
The P38 needs a good strong battery to run properly, any issue in that department will throw weird fault codes.
Hope that is of some help, good luck with it!
Cheers, Pete.

[zzsteve]

Thanks Pete,
13.6 at idle and 13.9 with some revs (2000)
Some sites say this is ok, but I would prefer to see 14.2 or better. I have a new reg and brushes for the Marelli alternator now - maybe worth a try.
Steve