Control Module replacement on 1997 850

DavidB · Post by **DavidB** » 11 Sep 2016, 00:14

Hello,

I'm completely new here but I'm kind of desperately in need of help.

TL:DR need to replace the ECM and TCM (which together are the PCM computer chips) in my Volvo 850, How much trouble am I going to have if I just buy these used from eBay and slap them in? (it has the level on it so it is super easy to replace)

Longer story: the mechanic tells me that I need to replace the Power Control Module in my 850, they are burnt out. However, he refuses to replace these with anything other than new OEM parts, making the repair cost USD $ 2200, which is more than I paid for the car. I need the car up and running ASAP since a car we were borrowing is no longer available. I've seen these two modules on eBay for as low as $35, the mechanic thinks that they need to be programmed but a fella named RobertDIY on Youtube does not think that is the case. The situation is such that I really need to just buy these and put them in the car and see if it works, any advise on whether or not this is a good idea would be greatly appreciated.

Also, I grant you all of this is presuming that the diagnosis is correct and that whatever caused the burnout will not happen again. Since I will eventually get asked, this is what is going on with the car: it dies if I do not keep pressure on the gas pedal, and it needs more than you would think it should need for just an idle. I've replaced the fuel pump, the fuel filter, and replaced the IACV (which I sent back when it didn't fix the problem.) The mechanic then looked at it for a few weeks (Meineke) and finally came back with it being the PCM, they said it looks burnt out (it does) and that there was no voltage coming back out of them.. so there ya have it...

Thanks in advance for any help provided and I hope I can be a good member of your community here!

Post by **abscate** » 11 Sep 2016, 05:32

The scenario you describe is so common I eventually put it into my signature.

Mechanics who have no clue what's wrong with your car tell you it's the ECU so you go somewhere else.

Change mechanics and find someone who can diagnose your " no idle condition" without throwing parts.

Post by **kahl** » 11 Sep 2016, 06:47

1. Roberts guess is better than most people's fact
2. Get the used modules and plug them in...see if it fixes problem
3. Not sure where Auroa is located...could be other members in your area that can assist
4. Follow abscate's advise

Post by **misha** » 11 Sep 2016, 07:38

Listen to what abscate,robert(rspi) and kahl are saying!

I just need to add....just make sure you have the same Bosch(ecu) & aisin (tcu)numbers on replacements.

Post by **tryingbe** » 11 Sep 2016, 08:06

Run, not walk, RUN from that so call "mechanic". He priced it high so you will get out of his shop since he has no idea what is wrong with your car. Stay away from oil lube place to do actual diagnosis work.

You might want to give us a few info.

Is it a TURBO? Location? Check engine code? Vacuum leak would do what you describe.

Post by **cn90** » 11 Sep 2016, 09:10

The mechanic is wrong, no need to program it.
Programming is needed in much later models.

The ECU, TCM rarely rarely rarely goes wrong.
If you have access to junk yard then get used modules and test them.
Or buy from ebay, test them, if the diagnosis is wrong (car does not run even with new module), then re-sell those modules on ebay.

I have a hunch your problem is bad MAF. This happened to me at 100K miles, a new Bosch MAF later, car has been fine the last 80K miles.

Post by **BEJinFbk** » 11 Sep 2016, 11:45

Meineke? I think I've found your problem...
The farther you get away from that place,
the closer you'll be to an actual solution.

Put the idea of "Bad Modules" out of your mind.
That guy telling you that they need programming,
have to be new OEM and that both the engine AND
transmission modules need to be replaced are all
huge red flags! That guy is in waaaay over his head.

It is MUCH more likely that you have a more
conventional problem. Possibly more than one,
but the electronics are most likely perfectly OK.

If you're in the Denver area ( Please clarify which
Aurora you live in with your sig ), check out these guys:

Volvo Specialists
36 South Santa Fe Drive
Denver, CO 80223
303-722-8658

What ever you do, start fresh with a trustworthy opinion
from a well respected independent Volvo shop that's familiar
with these older P80 type Volvos.

You can also get a lot of help from the knowledgable folks here.
Is your check engine light on? Have you plugged in an OBD ll scanner
and checked for any stored diagnostic code? We Can Help!

DavidB · Post by **DavidB** » 11 Sep 2016, 23:44

Thank you all for the prompt replies. So an answer and a question. I am in Aurora CO so, yes, BEJinFbk I will contact that Volvo specialist you mentioned, but I did get the TCM and ECM on eBay and so will try those first.

I got a check engine code a while back when the trouble started and the guy at O'Reilly said that it pointed to the Idle Air Control Valve (which at the time I didn't know what that was.) I haven't had it scanned since, though I could ask Meineke what codes they got from it. My wife had it towed a ways away and I am borrowing my mothers car so it is a hassle to get over there easily

Non-car related personal story: (she got tired of my trying to fix it and her boss suggested Meineke, since she was borrowing his car and he offered to cover payment on the mechanic until we could pay him back, it seemed like an okay move at the time. As a note, when I told Meineke they had not fixed it they offered to credit us with the amount the boss was charged, so the whole thing is a bit of a weird mess.. still haven't quite figured out how that worked out, but the boss wanted his car back and now I need to get this one fixed asap.... )

Question is: I don't know exactly which 1997 850 the car is, it doesn't say inside the door or on the title, but from my part search on eBay all of them did say it was for a turbo (P09189155 & P 09442107), how else might I find out?

(I'll fix my sig later, wife needs me to come pick her up)
Thanks for your help and support everyone!!

Post by **erikv11** » 12 Sep 2016, 00:26

There are a few ways to find out which 850 it is, here are some:

(1) post picture of the engine bay with the hood up, we can tell you if it has a turbo or not. But there are two kinds of turbo cars.

(2) use the VIN, do you have that number anywhere handy? Use this page http://new.volvocars.com/ownersdocs/199 ... n1997.html and find out the engine code. Code 55 is non-turbo, the rest are turbo, tell us the code.

(3) Does the car say "GLT" on the back trunk lid (sedan) or hatch (wagon)? That's the low pressure turbo in 1997.

You can't mix turbo and non-turbo ECUs, there are even some turbo ECUs you shouldn't swap around. So figure that out before you install anything, unless the Bosch numbers match exactly the ones that came out of the car. But I doubt there is an ECU problem.

If you can get the OBD codes from Meineke and post them, that will help out tremendously.

Post by **abscate** » 12 Sep 2016, 00:50

We will get you fixed up. I doubt it is serious

Old guy advice from 1968...

Dad: Keep your personal and work life separate
Me: ok.

Still applies.