Inhibitor switch failure?

[GavinC]

'95 960 190,000 miles.

Do the following symptoms point to the failure of just ONE component - the inhibitor switch?

1. Stall/cut out... without warning at low revs... very occasionally. Shift selector to 'P' or 'N' (of course) to start, starts immediately, idles silky smooth and drive off running as sweet as ever.

2. Attempt to start after standing overnight... turn ignition key, all dash lights display as normal but no sound whatsoever from starter motor, so no crank. Shift gear selector back and forth a few times, turn key... cranks immediately with full vigour and fires up as normal. Again, plays up like this just very occasionally.

3. Flashy arrow syndrome... again, just very occasionally; moving off after parked overnight, flashy arrow shows AND gearbox has shifted itself into 'W' mode. Always 'cured' by switching ignition off and 'rowing' the shift selector back and forth from 'P' to 'W' a dozen or so times. Flashy arrow may not disappear for quite a few miles after that however gearbox reverts to 'N'/normal mode immediately.

Can live with last two items, but not the stalling... for obvious safety reasons. This otherwise fine car will be scrapped if I cannot resolve the stalling issue.

QUESTION: What's the likely cause? Inhibitor switch only? (Bearing in mind that all three of these problems have always been temporarily 'cured' by shifting the gear selector.)

Component cost and garage labour hours ballpark, please?

Despite my presumption that it is simply the inhibitor switch, any and all advice would be much appreciated... NB

If there is any chance at all that another component is causing the stalling/cutting out problem, I'd like to know. Any diagnosis clues, too.

Thanks in advance.

[Steve940estate]

It sounds like that it might be part of the problem although it shouldn't cause the car to stall, unless the 960 is wired up a lot differently to a 940.
As far as I know the inhibitor, like the alarm immobiliser only cuts power to the starter motor, so the car shouldn't be affected when running.
On 940s I have read on here that ignition switches can give problems like cutting out and not starting intermittently, crankshaft position sensors can do the same as well.

Hope you find the problem.

[Dan R]

I second Steve's opinion on the PNP switch would not cause stalling. The PNP switch can be removed, cleaned and regreased saving the cost of a new part. That will take care of the no start issue.

The stalling could be the ignition key, but I would suspect some wires are grounding out in the ignition system. Those located on the top of the head under the "Volvo" cover have been know to chaff and short out. The timing is about right for Volvo wire insulation to be cracking and falling off, they are way ahead of their time with the invention of biodegradable wire insulation. Both my '85 240 and my 960 and the wires.

Have you checked for any stored codes? Not all stored codes will illuminate the check engine light, only those effecting emissions. In the absence of any codes, then look for a fuel deliver problem or an ignition problem. The fuel pump relay can be a suspect, the ignition and injection relays too. All of these item are not very expensive and well under the cost of scrapping the car. The trick is to replace the correct part.

Another thing to try that won't cost anything but some time, disconnect the plugs under hood on the wiring harness (loom), clean them with some electrical contact cleaner and a small seal pick, bend the contacts to tighten them. Do the big plugs too. Especially those for the...... no just do them all, all of the sensors, it will take a couple of hours, but that may just fix a weak signal some intermittant sensor signal.

Good luck, let us know how it progresses.

DanR '94 964 343,000 miles (109,000 on the new engine)