95 PA Ultra with OBDII?

[gkook]

I have a 95 Ultra and the check engine light on with the TC light. The vehicle runs well, no drivability issues, the ABS works but not the traction control. This only has 96k miles on it.

I brought the car to O'Reilly for an engine scan and they said it is OBDII not OBDI, but couldn't communicate because of the TC problem. I then brought it to Midas and their scan said the PCM is no good and that this has 1996 electronics, and quoted $750 for a new PCM and re-programming.

My question is don't the 1995s have the PCM with an EPROM (so I could just get a used one and change the EPROM)? Or was there a cross-period in which Buick put PCMs with un-replacable EPROMs (1996 and newer) in the 1995 PA Ultras?

Is there a resource that shows what electronics were installed according to the VIN? (1G4CU5212SH603018)

Thanks for any insight.

[maxwedge]

95 is a transition year, sort of obd1.5, only a highline scanner will work. The traction control is part of the abs and will need to be scanned with an abs function scanner. Just about any garage would be capable of checking this for you, the free stuff at the parts stores, no.

[Tech II]

What ever you do, don't go back to those two places, because they didn't know what Max and any good tech would know.......

[gkook]

Thanks for the info guys. In the event, for my future reference though, since my 95 Ultra has the OBD1.5 or (2?), the PCM would still be a 1995 with the removable EPROM, is that correct? And if so, is there any othering programming that would need to be done to the PCM if I bought a used or reconditioned one?

Midas said their scanner does do the ABS function and insisted that it is the PCM. The codes they pulled were: PO321, P0361 and C75, do these make any sense?

This all so confusing to me...but I sure do appreciate all the knowledge everyone brings to the table.

[Tech II]

So, just by looking up codes, they determined that it needed a PCM?

Other code was probably C0075......

personally, I'd go to a dealership.....

[Jrs3800]

I think I agree with Tech here... You may want to take the car to the dealer and have it read...

But I see what seems to be a common code that pops up when the 94-95 3800 PCM gets funky( going belly up )... The P0361 is more than most likely a P1361, some tools display this as a P0361 for whatever reason..

The 1361 is basically a code for the ICM to PCM handshake, after 400 Rpms the PCM takes over control of the timing, You actually start the car in Module Mode Timing( Ignition Control Module timing mode ) and after 400 Rpms the PCM should take over... A lot of the time this code seems to pop up when the PCM fails to do this.. But lets not assume the PCM is bad yet...


The P0321 is a spark reference circuit issue, so its also possible that you could have a bad ICM, bad crank sensor or wires to( its one complete harness )...


Its hard for me to say which items are causing the problem... But when I traveled in my 95 Bonneville the running joke was I had the only Bonneville with a Trunk PCM as I always had a spare in the trunk just in case... I did the exact same with my 95 Trans Sport that used the exact same PCM... we grew tired of this and updated both cars to 97 PCM and harnesses PITA but works... Thats another story..


Your 95 Ultra uses the 94-95 PCM used in all 94-95 3800 powered C and H bodies as well as the 94-95 3800 U Body Vans... So this 95 Ultra is an OBD1 Car, but it uses the OBD 2 Connector and OBD2 codes but the PCM uses OBD1 Protocol... Some tools will not read these GM cars, the tool has to have the capability to read these above cars... Strange I know...

My head says you either have a PCM issue, ICM issue or both...

Good Luck

[gkook]

I am kind of resisting to go spend another $100 on a scan.

But, I did buy a subscription to Alldata DIY. And as an FYI, I used promo code HYBRIDREPAIR and was able to get 3 yrs for $21.95! Not sure how long that code is good for though.

I do have another 95 ultra that I am selling (very rusty under-carriage and rough body), would I be able to swap PCMs and see if that is the problem? The Midas idiot said it wouldn't work because reprogramming was needed. But after further research, these 95s should be plug and play with no dealer re-programming right?

I will await to see if anyone can confirm this for me...I hate to make things worse.

Thanks!

[Jrs3800]

Yes the PCM's are identical... There is no flashing with these PCM's simply swap out the EPROM and you should be good to go... This will be a good test as you have a car you can borrow from..

Really the other car should have the same EPROM... The one good thing was GM used the same PCM over a wide range of cars...lol

Disconnect the negative cable, R&R the PCM, Hook the Neg cable back up and see what you have...

Good Luck...

[gkook]

Thanks Jrs3800. Hopefully I will get time in the next couple of days to try this after I finish digging out from our 16" snowfall! (And take temporarily take off the for sale signs.)

[gkook]

Well, this has now turned into an intermittent problem. Car started right up tonight with no lights.

I have reposted this problem in a new thread titled "95 Ultra Intermittent SES & TC Light".

[Blue Bowtie]

That connector at the base of the ICM is pretty suspect on many that I've seen. Make sure the ICM has a good ground, too. The base of the heat sink tends to corrode and lose conductivity. A good cleaning and fresh application of silicone grease might not be a bad idea.

[gkook]

This sure can't hurt, I will give this a try this week end.

Thanks Blue Bowtie.