new pnp switch fails on my 97 960 volvo

pnp97volvo · Post by **pnp97volvo** » 15 Nov 2012, 18:51

I have replaced my PNP (Neutral safety switch) 3 times once at 147,000 miles; 2nd 161,000 and third at 167,000. They continue to fail. Does anyone know the root cause???

Post by **jimmy57** » 15 Nov 2012, 19:24

I had that history with Scantech sensor and they warranted it and it failed again in 8-10K miles so I replaced it with dealer part and it is still going.
Were the parts Volvo parts or aftermarket?

pnp97volvo · Post by **pnp97volvo** » 15 Nov 2012, 19:58

three failures were volvo parts the fourth attempt is going to be aftermarket wish me luck

pnp97volvo · Post by **pnp97volvo** » 21 Nov 2012, 13:18

I think I have found my problem. As I was installing the male to female plug I noticed that the female half, pins were recessed in the plug housing unit. I then manually pushed each receptacle (wire lead) deeper into its plastic receiver housing. The lack of copper to copper contact may have caused a short (arching) causing the Plastic coating on the oppposing side to blister. Anytime it, the pnp switch, has failed the white plastic coating on the PNP reverse side has been blistered. HOPE I"M RIGHT..........Seems as no others (73 hits) have a comment.

Post by **jimmy57** » 21 Nov 2012, 13:27

The aftermarket ones distort internally and give codes for the gear position sensor and the trans has shifting issues.
You never told us what the failures were or the behavior of the car.
The plug having melted connectors is nothing ever reported here.
The failures of the gear position sensor/reverse light switch/start inhibitor switch that are seen repeatedly are for the contacts on the internal surface wearing out or the wiping contact for those surfaces wearing. The aftermarket items have proven inferior in those areas.

If the pins re not going fully into connector then you get heat from overcurrent from the reduced contact surface area. You've probably had an outlet in your home do that at some point with a high watt consumer plugged in.

You still have not listed what the failure is so the help will be no better than the symptoms listed.

pnp97volvo · Post by **pnp97volvo** » 22 Nov 2012, 16:39

Symptons (0740) at 147,000 flashing rpm arrow and WSE flashing but, it would still start. Code 0740 constitued the repalcement of the PNP. I changed the PNP (Volvo part). Worked fine until 161,000 miles. Then the same code ocurred 0740 flashing lights and, it would start. I still drove it for about 130 miles and it finally stopped cranking. Changed the PNP volvo part again and it would start but, the code would not go away. Took it to Volvo service they noted P0321 code "TRANSMISSION LOCK-UP SOLENOID FAULTY". So, I purchased the solenoid OHM-ed old and new and noted the soleniod was bad. Volvo service wanted to rebuild the transmission not just replace the Lock up solenoid. After repalcing the Lock up sloenoid the codes went away. I still had the new PNP switch installed. At 167,000 0705 appeared. Again, I changed the PNP but use an after market part from Carquest. Cost about $25 less than same as Volvo however, it was in stock and I did not have to wait 5 days like I did with Volvo. So now it is operating as advertised just think it may have been the contact surface that was causing the subsequent second and third issues. Please advise...............

pnp97volvo · Post by **pnp97volvo** » 10 Feb 2013, 19:07

Been almost 5 months thought someone out there was a gifted volvo mechanic. Looks like I'm it. Please comment