850 Reverse lights working off and on

volvo_boy_88 · Post by **volvo_boy_88** » 22 Aug 2009, 23:43

When I put my shifter in reverse, the reverse lights seem to work whenever they want to. I noticed however that if I toggle with the shifter the lights will come on, but I have to hold the shifter just barely before Nuetral (or just in the right position) in order to keep the lights on. I took apart the center console on the inside of the car to see if there was something not contacting in the shifter, like a switch or something, but I didn't see anything for reverse. I looked more in depth with the Haynes Repair Manual and saw the Reverse light switch that is connected to the tranny. Could this be the problem? Has anybody else ever had this problem before? How do I fix this? I don't want somebody running into me and it being my fault for malfunctioning reverse lights.

Post by **Ozark Lee** » 23 Aug 2009, 02:24

Your PNP switch is failing.

Things will only get worse from here and, on the first cold winter day the car won't even crank.

The part is relatively inexpensive - don't buy the scan tech junk - and easy to install. The hard part is the alignment but MIJ has a great technique using a mirror behind the car in the repair database.

...Lee

volvo_boy_88 · Post by **volvo_boy_88** » 29 Sep 2009, 11:37

What is a PNP switch and what does it do? Where is it located? I have had a few rare days where I turn the key and all electrical components work, but the engine doesn't even crank when I turn it all the way. The brakes seem locked too, where I cant push the brake pedal all the way down. Does this have to do with the PNP switch? Could you please provide me that link to fixing the switch?

Post by **Ozark Lee** » 29 Sep 2009, 12:29

The PNP switch is the Park Neutral Position switch. In reality it has positions for all of the gears but the starter will not engage unless the gear shift is in park or neutral. When the switch starts to go out it is common for the starter to not function. The colder the weather gets the worse the problem becomes.

It is located on the top of the transmission.

http://volvospeed.com/Repair/pnpswitch.php

A tip to align the switch without the special tool is here:

https://www.matthewsvolvosite.com/forums ... 7963#57963

...Lee

volvo_boy_88 · Post by **volvo_boy_88** » 07 Oct 2009, 00:25

Is the PNP switch the same thing as the Backup Light Switch according to the Haynes repair booklet? If you have it for the 850 look on page 7A-4 and refer to illustration 5.2. It seems like it is to me since you are saying that it is located in the top of the tranny, as this seems to be too. If so, can I replace it with this:

http://www.autopartsdeal.com/catalog/?N ... lvo&md=850

Do i even need all of this to replace it? Please let me know. Thank you.

volvo_boy_88 · Post by **volvo_boy_88** » 07 Oct 2009, 00:50

Or maybe even just this???

http://www.pelicanparts.com/cgi-bin/sma ... 7%29%20%20

volvo_boy_88 · Post by **volvo_boy_88** » 07 Oct 2009, 00:54

Okay, so I did a little reading and studying and found that the PNP switch is not the same as the Backup Light Switch (lol, I can just picture some of you reading this just saying, "DUH!!! I knew that" or shaking your head and saying, "Amatuers")

It's all a part of learning right?

So now my question is which do you think it is and what should I do? Should I take a look and see if I can pull out the Backup switch to see if it needs replacing, or what? Ideas, thoughts??? Please help...

Post by **polskamafia mjl** » 07 Oct 2009, 01:34

I have the same exact problem. It's the PNP switch. Sorry, lol.

Post by **Ozark Lee** » 07 Oct 2009, 01:54

The reverse lights are controlled by the PNP switch on an automatic transmission. The items you posted links to are for cars equipped with a manual transmission. There is no stand-alone reverse light switch on 850s with automatic transmissions.

...Lee

volvo_boy_88 · Post by **volvo_boy_88** » 20 Oct 2009, 10:55

Ok, thanks Lee. I will look into replacing the switch later. I can deal without it for now. I have a major oil leak I need to fix first on top of a cracked radiator

No fun...