General: 850: Gearbox problem maybe ????

[damrabbit]

Hi

Car is Volvo 850 TDi automatic 131,000 miles

I took the caravan out this weekend and when I got to the site and booked in the car would not start.
It gave the same symptoms as when I've tried to start the car when I mistakenly left in drive i.e all dashboard lights but no attempt to turn I had driven the car quite hard and wondered if perhaps the gearbox had overheated as when I tried 30 minutes later it started fine and when I came back I took it easier and again the car was fine, temp guage on dash stayed fine on both journeys with no other warning lights at all

Any suggestions please

thanks

[thetroublemaker]

Could be one of a few things.

1 - Search PNP switch in this forum. The quick and dirty test is to run the selector through all positions 30 or 40 times. If it needs replacing its £150 and 2-3 hours from memory.

2 - Could simply be a tired starter motor, cheap repair if so.

3 - possible curveball could be the inductive pickup round the ignition barrel for the immobiliser but I THOUGHT that only affected the ignition circuit - ie the car would crank and crank but not fire....but mines a tdi so it may work differently.

Don't write the box off I don't think that's the failure mode - ie it would die and slip and you would go into limp mode normally.

[capt jack]

Do the reverse lights work? If not then the PNP switch is the chief suspect.

It can be replaced, or it's possible to buy a repair kit.

The PNP tells the car which gear is selected and acts as the inhibitor, preventing starting if the car is not in P or N.

The internal contacts wear out, the first sign usually being the lack of reverse lights. Cleaning up the contacts by moving the selector energetically as described is a temporary fix, but ultimately you'll need to sort it out properly.

Cheers

Jack

[Paffel]

Originally Posted by capt jack

Do the reverse lights work? If not then the PNP switch is the chief suspect.

It can be replaced, or it's possible to buy a repair kit.

The PNP tells the car which gear is selected and acts as the inhibitor, preventing starting if the car is not in P or N.

The internal contacts wear out, the first sign usually being the lack of reverse lights. Cleaning up the contacts by moving the selector energetically as described is a temporary fix, but ultimately you'll need to sort it out properly.

Cheers

Jack

My reverse lights sometimes worked, sometimes didn't - and it went into limp home mode if I selected L or 3. My contacts were completely shot in the PNP switch.
You can pick up the metal copper contacts for a few pounds (£10), then it is a case of removing the switch and dismantling. You'll also need to align the switch on refit, but this can be done with a pair of straight edges, or folding metal rule, etc.

There are a few guides dotted about that look complete, a search on Google for PNP 850 switch replacement brings up http://www.matthewsvolvosite.com/pnp...-cleaning.html

[damrabbit]

Cheers for that
Will the reverse lights not work only when it plays up or all the time as the gearbox is perfect at the moment and as yet no limp mode even before or after the event

[capt jack]

The reverse lights would work erratically, and working the selector back and forth will fix it temporarily. Like any intermittent electrical fault, it is very frustrating until either it's fixed, or it goes plop altogether.

Cheers

Jack