CEL with flashing up arrow on 1995 850

driver850 · Post by **driver850** » Mon Aug 13, 2018 2:28 pm

I have been having an ongoing issue with the CEL coming on and flashing up arrow. This car has 50k miles by the way. A year ago, when the CEL and flashing up arrow first happened, Volvo repair shop #1 said it had code 232, and replace the vehicle speed sensor. The problem appeared to go away. A year later, the same CEL/arrow resurfaced, and Volvo shop #2 said the TCM needed was bad and needed to be replaced (they said that they were seeing a lot of codes, and tested the components that those codes pointed to, but the other components were ok) - so I paid them to replace the TCM. Four months later the CEL/ flash up arrow reappeared. The code showing is P0500 which I have been told is related to the speed sensor. I've read on this site about "rowing the shifter through all the gears", and each time I've had this issue, I've tried that. Sometimes it clears the flashing up arrow (but not the CEL), and sometimes it doesn't clear the arrow. The car seems to be running fine - I don't notice anything related to shifting - except for one recent time when I put the car in park and it seemed like it didn't downshift (the motor was a bit loud). (also recently I had the spark plugs/ignition cables/distributer cap replaced but can't imagine that that is related). I'd really appreciate any help. thanks.

Post by **RickHaleParker** » Mon Aug 13, 2018 3:12 pm

Check the wiring harness to the TCM (Transmission Control Module) . May sure the connector(s) are clean and tight, wires are undamaged. Do the same for the ECM.

What Engine and Engine Control Module do you have?

driver850 · Post by **driver850** » Mon Aug 13, 2018 6:55 pm

Thanks for your suggestion. I've brought the car back to the shop (dealer) that replaced the TCM 4 months ago and am waiting to hear back from them. I will ask them to do that - I don't know a lot about repairing cars - but really like this car and would like to keep it. Its a 2.4 liter, 168 HP, - 854GTA (not a turbo). Not sure about the ECM - the original papers say "electronic self-diagnostic driveline management system"...

Post by **Ozark Lee** » Mon Aug 13, 2018 6:59 pm

It may well be a PNP switch that is going bad. They all do go bad eventually and if it is original on a '95 it is overdue. Given that things have changed at times when you row the shifter that is my first choice as to the culprit.

...Lee

driver850 · Post by **driver850** » Mon Aug 13, 2018 7:04 pm

Thanks very much - yes it is the original PNP switch. Can they troubleshoot to verify that it is the PNP switch before replacing it? Or is it easier/cheaper to just replace it? I am already thinking that the TCM never needed to be replaced....

Post by **Ozark Lee** » Tue Aug 14, 2018 9:27 am

Since the PNPs go out intermittently they are very tough to diagnose with a meter. One easy and obvious method is to look at the reverse lights while someone puts the car into reverse. If they sometimes don't illuminate or flicker then it is a "lead pipe cinch" that the switch is bad.

They can sometimes be repaired by disassembling them,cleaning out the dried up grease, and re-greasing them but over the years the contacts get worn and they are just pretty much done at that point.

...Lee