My OBD-1 port on my mint 1988 Firebird 2.8 AC Delete does not work. The engine works perfect and the engine computer will activate the check engine light is there is an issue. I am wondering if this yellow thing behind the dash is a buffer device between the OBD-1 port and engine computer and possibly it has failed. I opened it up, one IC, a few diodes and resisters, looks like a buffer to me. Is the thing swappable from 5L and 5.7s or the 3.1 ? Thanks for you comments. Glen

 

That is the vss buffer used to split signal from vehicle speed sensor (vss) to the ECM, speedo and cruse control if equipped. Has nothing to do with the ALDL or communication from the ECM. What cable are you using and how do you have it set up?

 

thank you, understood on the speed sensor and cruise as this car has cruise control. I have a brand new Innova 3120 code reader which comes with all the right connectors and cables. It does OBD1 and OBD2, the unit works in OBD2 mode on my other car. When I connect it to the F Body the reader asks a few questions, certain vin digit etc but I get no responses. I have a friend with an 1987 Chevrolet pickup so we are going try it on that to isolate if its the reader or ECM. If you have any thoughts, appreciate it. The reader is brand new. My car was stored from 1999 until last year. Love to have the reader working. Thank you

 

Have you contacted Innova for support?

 

If memory serves me correctly, those small scan tools are not self powered. Meaning they slave off of the cars power when plugged into the OBD port. I know on the later OBD2 GM's the power port is usually pin 16 which is on the same circuit as the cigarette lighter. So if the lighter is not working (fuse blown usually) then the scanner won't work. Not sure on the OBD1's though....but it might be worth looking into.

 

I have the Innova 3140. It read OBD2 just fine. I tried on one of my OBD1 cars and came up with 11 codes and most codes weren't available on the ECM. So I hooked up my laptop and I only had 1 code.

So it could be the scanner. My old Auto Xray was a lot better for OBD1, it read codes and did live data.

 

thank you all

 

Scan tools are a crapshoot and not really useful for the ALDL. You can do much, much more with a USB to ALDL cable and an old laptop. It is generally cheaper too - old laptops are often nearly free and so is the software to do the interfacing. You just buy the cable and you are in business.

GD

 

thank you GeneralDisorder