1996 Volvo 850 No Start/Flashing Up Arrow

TBrown00 · Post by **TBrown00** » 19 Sep 2016, 20:35

Hello everyone,

I have a 1996 850 GLT that about 3 years ago had a crank but no start issue. It would crank and fail to start but if I tried a few times it would start right up usually. Sometimes I would need to wait 10-15 minutes and try again and then it would magically start. I found there was a spark and fuel pressure to the rail so I hit the injector relay which fixed the problem. Fast forward to now and I was having sporadic issues over the past month, mostly when it was cold. Same thing this time, pressure to the rail but no start (I didn't check for a spark but assumed the injector relay was finally dying instead of being sticky). I replaced the injector relay but the next day was back to the same problem.

When I replaced the relay I noticed that the wire terminals in the harness were loose and would move around when the relay was inserted so I assumed it was due to a bad connection at the relay. I removed the relay again and played around with the wiring removing and reinserting the relay a few times and eventually heard/felt it click and was sounded like fuel spraying into the engine and then it started right up. When I got back in the car, I noticed the up arrow was flashing and I had a TPS code. I researched that and found a post stating that the injector relay could cause that so I chalked it up to that and went on my way.

I hadn't had any issues for a couple weeks until today. Except for one day last week when it idled terribly upon starting (it would idle anywhere from 500-1400) and was very rough. It also tried to stall out once or twice around 400 of 600 but it raised the RPMs and kept running. As soon as I shifted into drive the idle smoothed out and I had no other drivability problems that day or since. It was an isolated incident.

When I got home today and tried to restart the car to test/recharge my AC, it wouldn't start and I had the flashing up arrow. Pulled the codes and had P0120 for the TPS again. Car started after that, cleared the codes, and the arrow went off. Turned it off, went inside and grabbed the R143 can but the car wouldn't start again with the arrow and P0120.

When I pulled the codes this time, only 1 module showed up. I have the Autel 619 and usually 2 modules show up when I select OBDII. One is useless and doesn't really have any info in it and the other has all the info you would expect. Right now the module that is working only has the engine code - I can't access any live data.

I guess my question is, since only 1 module is showing up and I can't access any data, does that mean the ECU is dying? Or is that just a coincidence and I need to fix either the wiring harness at the injector relay or test/replace the TPS?

Thanks for reading to the end and in advance for any help!

TL;DR: car won't start (will crank but engine won't start) and I have a flashing up arrow on the dash (code P0120) with hardly any info on my code reader (AU619). Possible ECU issue or just coincidental and more likely injector relay wiring or TPS?

Post by **tryingbe** » 19 Sep 2016, 20:49

Replace the injector relay plug already!

TBrown00 · Post by **TBrown00** » 19 Sep 2016, 20:58

I did 2 weeks ago. Sorry if that wasn't clear in the OP!