95 OBDII ? and scanner.

[534BC]

The last one is what I have,



I think, lol. I'm going to auto-zone or dealer to confirm before I purchase my own equipment.

[MT-2500]

Originally Posted by blazee

Rental Blazer is correct that there are three different systems. He is, however mistaken on their locations. The first system is located behind the dash and is interfaced using an OBD I assembly line data link connector. This sytem is completely OBD I and codes can be retreived by jumping the pins. The second system is located behind the dash, and is interfaced with an OBD II style Diagnostic Link Connector. This system is OBD I, but requires a special scanner to retreive the codes. The third is located on the passenger side fender, above the coolant reservoir, and uses an OBD II style connector. This system is OBD II, and codes can be retreived with a generic OBD II scanner.

Thanks for the info Blazee.
I have not had the pleasure to run into the one with OBD11 connector with pcm behind.
Or I had the special scanner and did not notice it.
Is it on a 4.3 W or 4.3 Z or both.
MT

[MT-2500]

[quote=rental blazer]

Originally Posted by MT-2500

The certified sticker sometimes gets mixed upp on what one it is.
Well the location of the PCM or VCM and the diagnostic plug is the first clue.
Here is a OBD11 conector.
http://www.troublecodes.net/OBD2/
And here is the OBD1
http://www.troublecodes.net/GM/

One computer behind glove box is a PCM and one on the fender is a VCM.
What is the 3th one?
MT[/QUOTE
the 3rd being VCM/A

Thanks for the info rental blazer.
Then the VCM computer on the fender comes two ways?
I will have to heep my eyes open for them.
MT

[BlazerLT]

Originally Posted by rental blazer

mt 2500 I've gotta say i disagree I read on the muauls behind glovebox is obd2 and on fender is obd1 there are actilly 3 diffent boxs for 95... so yes its confuseing i do however have the box he speaks of that says obd1 cerf. on my 95 and with the 2 port inside the car and guess what...I contacted genral motors with my vin and they told me it was obd1 so if you want to be sure go to the dealer have em run your vin...thats the easyest way to know..and yes 96 and up were all obd2 .

You are wrong.

Under the glove box is OBDI.

Ontop of the passenger side wheel well is OBDII.

Pure and simple.

[blazes9395]

Blazee is right, there are three. But lets go back a little further, starting with the ECM, PCM, VCM(A). The ECM is used for Engine Control Only, with the exception of TCC lock up - found under the dashboard. The PCM Powertrain Control Module, primarily used with the W engine from when the 4L60E was used in these trucks (about '92). This system controls, as its name implies Powertrain, ( engine control, transmission shifts, TCC lock-up etc), also found under the dashboard. The VCM(A) Vehicle Control Module, began with limited capabilities, meaning not full fledged OBD II in '95, but defiently certified at least for OBD I. Thats why the sticker says OBD I certified, not enough for OBD II, but well with OBD I requirements. (I also asked why the OBD I certified sticker was used on my '95 Jimmy, and thats the answer I got from the dealer, and hence the OBD 1.5 designation by many people.)

This is where the three different "systems" came into effect in '95

I know that there were two types of the PCM type systems that were used with the OBD I connector, and the OBD II conector. The PCM type system that had the OBD II conector was programmed differently and needed a scanner to read it. The scanner used what was a "manufacturer specific" type of conector. If the OBD I conector was used then the codes could be read by jumping the terminals. Both these systems were under the dashboard. The VCM(A) system was the third system used in '95, and the begining of the real changeover for the full OBD II system to be used, as required, begining in '96. This system could "usually" be scanned using a "generic OBD II"(not sure if all could use the generic conector for the scanner).

Very confusing to say the least, so I understand why some people who have an idea of these systems tend to want to stay away from these years.

[BlazerLT]

Most I have seen are either OBDII with the 16 pin or OBDI with the older connector.

Very VERY few are from the inbetween stages.

[534BC]

I just went to AZ today and the lady told me "no codes" and that it was obd2. I happened to know her also from a tire shop 10 years ago. smallworld.

[534BC]

Well, I'm not real thrilled so far with the software. I did get a scanner and some freeware. It works pretty good, but my vehicle supports very few sensors and I cannot seem to detect any misfires at all. I am wondering how any scanner would be able to tell which cylinder is misfiring and furthermore IF a cylinder was misfiring?

On to my Freeware. I downloaded 9 different ones for trials and freeware, out of the 9 I got 8 to install, 4 to actually connect and 2 to actually read any data and 0 of them to be useful.

The free one I got from scantoll.net is the most basic one and it works the best. A couple of them are pretty impressive if purchased, but I have doubts as to whether or not thy'd do a misfire on my vehicle. another thread perhaps.