PNP replace or clean?

NewToVolvo850s · Post by **NewToVolvo850s** » 02 Jan 2012, 17:43

My PNP switch is giving me problems.
-No reverse lights
-Cant go over half throttle
-Shifts weird
-Dash lights shut off when I go into drive
Should I replace it with a shop or clean it myself? Which is safer? This is my DD and wont be able to get around to it until this weekend

Post by **vjaneczko** » 02 Jan 2012, 18:36

Are you able to pull any codes? Seems like the problems are more then the PNP.

Regardless; I'd crack it open and clean it up. I read a write-up a while ago and it seems that the hardest part of the job is removing everything from the car to get at the thing in the first place.

NewToVolvo850s · Post by **NewToVolvo850s** » 02 Jan 2012, 18:47

I have no way to pull up codes. I will get autozone to do it tomorrow. How long of a job is cleaning the PNP switch? Is it better to clean it than replace it? Is it difficult?

Post by **erikv11** » 02 Jan 2012, 19:28

I have cleaned the PNP before. Getting to it is some work, took me 2 hours on an NA. Then pulling and cleaning another hour, couple hours to put it back together.

If you are going to clean it, you really must get replacement copper contacts. They wear out and get crooked, usually only one or two of them wear out but this is usually the problem, more so than just dirt and crud. There are three contacts in the switch. The best route is to get a PNP that someone is junking, or from a yard. Take it apart before you take apart your own. Then you'll know what to do with yours. Keep the best 3 contacts overall when you put yours back together, it will be good to go a long time.

There is a writeup on this site for cleaning.

I think replacing is faster and easier than cleaning/rebuilding, but also a lot more expensive.

Post by **jblackburn** » 02 Jan 2012, 19:34

Purely from a monetary standpoint, I'd clean it first. If that doesn't work, the 2nd time around is always much easier.

NewToVolvo850s · Post by **NewToVolvo850s** » 02 Jan 2012, 19:48

Thank you guys. What else could cause these problems I am having?

Post by **jblackburn** » 02 Jan 2012, 19:50

The PNP switch sounds like it could be the cause of most of these - the dash lights may/may not be an ignition switch (try jiggling your key).

A bad throttle position sensor can also sometimes account for bad shifting, BUT you also have the symptom of no reverse lights. I'd try cleaning and re-aligning the PNP switch (there's a trick using a mirror behind the car, or having a helper to yell at you when you get it into the "R" position and the lights come on really helps).

Post by **vjaneczko** » 02 Jan 2012, 19:57

If you're talking about the '95, you can pull codes with the breakout box in front of the ECU box, behind the passenger headlight. Do a quick search for tips.

The Volvo PNP is $176 and the ScanTech is $91 but I'd stay away from ScanTech due to their poor quality.
FCP Transmission Parts

waynej · Post by **waynej** » 03 Jan 2012, 06:43

I cleaned mine a few years ago and it's still doing fine. Total time R&R and clean was less than 3 hours. I just turned copper contacts over to get new surface instead of replacing.The problem is it comes packed full of grease which gets hard over the years and prevents contact. I removed all grease and flushed with solvent, then re-lubed with synthetic grease.

NewToVolvo850s · Post by **NewToVolvo850s** » 03 Jan 2012, 16:31

I started removal today and worked on it for 2 hours until dark and almost have it all the way out. I will clean it tomorrow and reinstall and align wednesday. hopefully this fixes my problems before the weekend.