1995 850 no reverse problem

Coasty · Post by **Coasty** » 14 Apr 2010, 18:58

A few weeks ago the car was stuck in 3rd gear. I was thinking PNP at this point. Then last week reverse and neutral both make the car go slightly forward. I replaced the PNP because I had an extra new one and then checked the engine codes. I got P0715 "input turbine speed sensor a circuit malfunction".

My question is this... would a bad speed sensor cause reverse to go out? I'm have a gut feeling the whole box is bad. Your thoughts?

FCPEURO · Post by **FCPEURO** » 14 Apr 2010, 19:59

Anything is possible but I have never heard of an speed sensor killing the reverse on a transmission. I am thinking it is a bigger issue with the trans itself.

Post by **Ozark Lee** » 14 Apr 2010, 21:38

How did you align the PNP switch?

A bad speed sensor tends to throw other codes as well as a malfunctioning speedometer. I think I would start by cleaning up the edge connectors on the TCM with contact cleaner. If there is no joy there move to the connector on the transmission and do the same thing.

These are no parts solutions that might work. I assume you have the blinking orange arrow and that the speedometer works OK based on your post.

...Lee

Coasty · Post by **Coasty** » 15 Apr 2010, 05:00

Thats correct, my speedo works just fine and I have the flashing arrow. Something interesting... no mater where i moved the the PNP switch (full deflection both ways) the reverse light stayed on when using the reverse light method. I couldn't get it to go out, so I just aligned the switch with approximately where the old one was based on the clean spots where the washers were. Could that be a clue?

Post by **Ozark Lee** » 15 Apr 2010, 18:56

I couldn't get it to go out, so I just aligned the switch with approximately where the old one was based on the clean spots where the washers were. Could that be a clue?

Something is messed up with the PNP switch. The reverse lights should trip on and off with a very small movement in the switch - it is very touchy.

...Lee

Coasty · Post by **Coasty** » 16 Apr 2010, 19:11

Interesting... what are the odds of having two bad PNP switches? This one was a Volvo part brand new out of the box. Could something other than the PNP cause the reverse lights to stay on like that?

Post by **Ozark Lee** » 17 Apr 2010, 07:04

A short in the wiring harness would explain everything. Electrical problems are always tough to find but they are very easy to fix once the problem is found.

...Lee

kiss4afrog · Post by **kiss4afrog** » 13 Oct 2013, 22:52

Coasty, any chance you're still around and can let us know what you found out on yours ??