This week a dealer mechanic told me that the PCM in my 95 Z28 was toast and needed to be replaced. I thought it was an OBD I even though it had a OBD II connector. He insisted it was an OBD II and replaced it with an OBD II. I thought all 95s had OBD I with OBD II connectors. Can the OBD I/II be visually identified? Mine had 4 connectors and an access door for a knock sensor. The Service Manager said the OBD I looks like a "tin can" compared to my which is a fairly sturdy unit.

The Service Manager showed me a GM document that stated the baud rate used to communicate with 95 PCMs is different than all other years. (95 is 160) Perhaps mechanics who worked on my car in the past mistakenly thought it was an OBD I because they used the wrong baud rate and just assumed it was just an OBD I. Comments?

 

if they did replace it with an OBD2 than you should be getting SES for several reasons. you are getting SES arent you?

 

The 95 engine is lacking a serious numberr of sensors that the OBD-II computer monitors. e.g. - crank position sensor, EEC flow detecter, AIR detector, after-cat O2 sensors.

The guys that developed LT1_Edit, and the cables for it claim they have never found an OBD-II PCM in a 95. There is virtually no difference in appearance between OBD-I and OBD-II LT1 PCM's. 4 connectors and a door for the knock module. But the inputs will not match, because of the missing sensors. The OBD-I PCM does not look like a "tin can".... they look identical.

The ALDL electronic signal interface is identical for sensor and parameter outputs... only the format of the DTC codes differs between OBD-I and OBD-II. A ScanMaster for a 94/95 will read everything on the 96/97's except the DTC codes.

Did you get a part # on the invoice?

 

Look at this sticker on your car and tell us what it says.

I think the mechanic is looney.

 

tell him to call gm and see what they would say. and the first year for obd2 is 96 in the f body.

 

Perfect advice!! That is the best and easiest way to check. Just look at the sticker.

All 95's are odb1 as far as I know. But some 96 models were sold in 95. Maybe the mech. is trying to overcharge you.

 

I have a question about the connector then. I have a '95 and it is OBD 1, but, the connector is OBD 2 (d shape 16 pin?). I have heard that they have done this, and if not, let me know.

 

my 95 has the OBDII connector also, it seems GM put both these connectors for 95 models. If you look in manuals it will tell you the same thing. I had to argue with the parts store guy about this issue when I wanted to rent a code scanner, so I'd say your mechanic is wrong.

 

Yep, mine does too. I think most 95's have the odb2 connector. Let's not talk about single cat/dual cat because that's another whole can of worms. It's seems GM did some half-assed $hit in 95.

 

there are 2 connectors:

14-pin found 93-94 F-bodies.

16-pin found 95-97(and maybe on up) F-bodies.

its not an OBD1/OBD2 connector... GM just changed it in 95

 

WSell guess what you arent the only one my friend also has a 95 z28 with obd2 and dual cats with pre and post 02s actually it is identicval to my 97 LT1 motor and the dealership informed him that he had OBD2 and his build date was late 94 so how does this happen?

 

I think all 95's came with the "OBDII type" connector and were OBDI. I think that some 95's did in fact have dual cats but these were California emission models only, but still OBDI. Again, "I think". I am sooooo confused.

 

Not 14, but 12 pin on the older ones.



unTAmedLS1:

Never heard of such an animal. They did make dual cat 1995s (California emissions), but no one has ever come forward with proof that theirs was OBDII. No LT1 OBDII f-body is identified in the factory manuals.
There are several board members that have dual cat 1995s and have confirmed they are OBDI.