I am trying to help my son with his Volvo 740. Intermittently, when he goes to start the car, it won't start. When he turns the key, to the on position, all of the lights turn one as expected. When you turn the key to the start position, all of the lights go off and the engine doesn't turn over. GO back to the one position and the lights turn back on.

If you leave the car alone for a couple of hours or more, it miraculously starts as if nothing was wrong. The starter was replaced a few years ago but it never really went away. It happens about once a month or so. There is no obvious pattern to the problem.

Appreciate any insight anyone would have.

EDIT: A couple of months ago, I took a look at the neutral safety switch as a potential cause but it seemed to test fine. What has me puzzled is that all of the lights go out.

Ian

 

There is a good chance that it's the PNP switch, maybe it's going bad. When it DOES NOT START, do you try to shift it to N and try to start it?

 

Is the pnp switch different than the neutral safety switch? I have tried shifting to neutral to start (when it doesn't start) in the past but it didn't help.

I just confirmed with my son that it didn't help this time. Would that switch failing cause the lights to go out when you move to the key to the start position.

If the pnp switch is bad, it it possible to by pass it? and confirm that it is the problem.

 

The ignition switch may be the cause... Not an expensive proposition.

 

I'm pretty sure that the "idiot lights" go out in all of these cars when you engage the starter.

I do not know of a way to bypass the PNP switch. Yes it would be the same as the neutral safety switch.

 

Thanks for the info. Much appreciated. I will let everyone know what I endup doing.

Edit

A couple of the other posts indicate the neutral safety switch under the vehicle near the bell housing on the drivers side. The documentation I have seems to indicate that on the 740 it is in the center console by the shifter. would you happen to know which one it is on the '88 740 Thanks

 

The neutral safety is located under the shifter on both 740's and 240's. 240's have a bypass connector under the hood expressly for the purpose of checking it but 7's, being designed for the American market, didn't get it.

 

there is a connector on that neutral/park switch, I think its on one side or another of the steering hump somewhat forward of the shifter. anyways, thats a convenient place to unplug the switch and plug in a jumper in its place.

otherwise, its a pink wire from pin 50 of the ignition switch that goes to the PNP switch, then a blue-green wire that goes through a couple bulkhead connectors and ends up at the starter solenoid. one of these connectors is the big block connector on the drivers side of the firewall, this has like 4 pins wide by about 15 high. the pink wire is on pin 24 and the blue-green wire is on pin 1...

oh, according to my diagram, the wires on the pnp switch side of the 4 pin transmission connector are blue and pink. on the car side, they are blue-green and pink or white. aanyways, direct connecting this pink and blue-green or blue wire together bypasses the PNP switch so the starter should always work.