850 1997 ecu re- programming required?

senior · Post by **senior** » 01 Jun 2013, 15:42

our 97 850 just wont start. checked out everything else and thinking ecu was going or gone bad. anyway I have one with the exact same numbers on it and can I just switch them out or is there a certain procedure I need to follow. came from same year,model,and automatic like mine. If there is one thing that I have learned from this site is never assume anything because if you just read you will find just what you don't know. thank you all

Post by **erikv11** » 01 Jun 2013, 16:13

For replacing a matching ECU, you can just pull one and put in the other. I like to disconnect the negative battery cable first but others laugh at me for that, say there is no need.

You said same year model etc; just to be sure are both turbo? Or both non-turbo? If yes to either question, you are good to go.

You can even swap ECUs between most years for the 850s. If the emissions setup was not the same on the two vehicles there is a chance a code will set when the ECU doesn't find what it is looking for, but that is inconsequential for the check you want to do. Go for it!

senior · Post by **senior** » 01 Jun 2013, 16:50

thanks for the positive answer I was hoping for. both are non turbo, should have stated that but would have if one was diff. I have worked on many types of auto's and they all are similar to a point but the volvo is in it's own realm when it comes to sensors,relays,modules and such. thanks again erikv 11

Post by **JRL** » 01 Jun 2013, 16:56

You need another non turbo ECU but I doubt the ECU is not allowing it to start unless somehow a pin on the bottom is broken

Post by **erikv11** » 01 Jun 2013, 18:49

If the ECU doesn't solve the no-start issue, cam position sensor and crank sensor are among the common culprits on these cars. I presume there is fuel and compression but no spark, based on you trying the ECU.

Post by **abscate** » 02 Jun 2013, 06:04

Erik is politely suggesting that a bad ECU is way down on the list of a no-start condition, I think.

senior · Post by **senior** » 02 Jun 2013, 09:56

we checked out all the sensors, relays, and most important every wire that we could possibly check for nicks,pinched, corroded or bad connections. with the luck I have it's probably not the ecu because it's free if I need it. if I don't spend a bunch of money on a part or two i'll still have a no-start. that's just they way it goes on my end. everyone on this forum are the one's that deserve to be rewarded for their devotion and persistence to help every person that only has to ask. my hats off to all of you, thank you so very much

Post by **shaker_chi** » 02 Jun 2013, 10:17

I had the same problem. I had fuel and spark and beat my head against the wall to figure out what it was. Finally, I picked up an ecu from ebay. I had to let it idle for about an hour once it started to burn off all the raw fuel in the system from unsuccessful starts. I also had to replace an O2 sensor. Make sure the ECU has the EXACT numbers or it won't work.

Post by **abscate** » 02 Jun 2013, 10:35

Ok, good luck senior. ....and come back if you are still stuck.

The Volvo gremlins tremble at the word "Matt's Volvo Site"...my driveway is green with the blood of slain Volvo gremlins....or blown radiators....

Post by **misha** » 02 Jun 2013, 16:09

senior wrote:our 97 850 just wont start. checked out everything else and thinking ecu was going or gone bad.

Ecu(s) on these cars rarely fails.In fact...i don't know anybody who had a bad ecu on these cars.

Can you describe to us what happened before the car refused to start(dead battery,empty on fuel....or it just refused to start one day)?

Like somebody said before....you need to verify a fuel pressure at a valve on a fuel rail(check if the fuel pump is running),spark,cam senzor(tdc sensor)and ...if battery was replaced i would check immobiliser.