First, the car history....It's a 1987 IROC that originally had a 5.0TPI with 5 speed...then I put in a 5.7L TPI and a 700R4 that came from a different 1987 IROC. I also swapped the engine wiring harness and the ECM, and the instrument cluster as well. When I did the swap, I noticed a tag on the tranny that told me it was a rebuilt. I've also tried to hook up all the appropriate wires to make sure everything works right, meaning, the park/neutral switch wire to the ecm, another wire from the P/N switch to the brake switch, and another wire or two for the tranny to make the torque converter work. Hope this makes sense.

Problem is, I'm not sure the torque converter is working, I don't have CC either, and the car is running very rich. Last weekend I checked over the vacuum lines for leaks, cleaned up a few cracked ends and/or replaced a few lines. Doesn't seem to make much of a difference. Now maybe there is still a vacuum leak somewhere I haven't found yet, but I'm not sure.

I was reading in a repair manual and found this paragraph about the VSS.
"Vehicle Speed Sensor: The VSS sends a pulsing voltage signal to the ECM, which the ECM converts to miles per hour. This sensor controls the operation of the TCC. On 1984 and earlier models the VSS is incorporated into the speedometer. On 1985 and later models, the VSS is mounted on the transmission."
Ok, so I crawled under the car looking for the VSS on the tranny...no such luck. From everything I can figure it should be on the tranny tailshaft and have some wires coming out...nada. NO wires, no VSS, nothing, not even a spot for it. The tranny does have a mechanical speedo cable however. So I'm wondering if I have an older tranny and speedo cluster? Would the VSS then be in the cluster? If so, is it somehow connected to the computer and sending the right signals? I don't know. How can I find out or check?

Need help please.

 

pull the codes.if you get a DTC 24 then the ECM is not getting the VSS signal.No code 24 mean all is good so you are looking for another problem with your TCC


Search for VSS Buffer info on here.

https://www.thirdgen.org/forums/post...727-post4.html
https://www.thirdgen.org/forums/post...803-post8.html

 

Ok, so I put a new bulb into the dash cluster for the check engine light (someone had removed it). When I turn the key to on, the light comes on, but once the engine is started and running, the light turns off. So my guess is, no codes being thrown.

So I did a diagnostic anyways. The manual says once the jumper wires are connected, a code 12 should flash three times in a row, once the key is turned on, and then be followed by any other stored codes. So I connected the jumper wire, turned the key to on, and only got a very quick two flashes, nothing else, no repitition, the light just stayed on afterwards. I tried this several times to confirm.

So what does that mean???

Also, what is the proper procedure for testing while driving the vehicle, the manual is a little vague. It says you shouldn't start the vehicle with the jumper wire connected. So does one connect the wire after the engine is running???

 

You don't.

Any codes generated are stored in the memory unless you disconnect the batt to clear them
So you drive , stop the engine , connect the jumper wire , turn key on ( no start ) and see if any codes are shown.

The only way to see what is happening with the engine running is to datalog to a laptop from the ALDL connector using this cable
http://www.aldlcable.com/

and some datalogging software

 

Ok, that makes sense. My manual said a driving diagnostic was possible with a carb'd vehicle, but mine is a TPI.

Anyways, what do you think about the diagnostic results I had. The two quick flashes are a mystery to me. Is this normal or not.

If no codes are being thrown, then I might have an internal issue with the tranny itself, possibly the T.Converter acting up, something I was hoping wasn't the case.