chevyman1217

I have been trying to figure out my speedo issues for awhile now and have tried a few different things but am running in to other issues now. I was told I should check to see if any codes came up but my check engine light is not on. I decided to check for codes anyway but have no power at the OBD 1 port for some reason. My speedo issues are as such- it works kinda-at 80 on the freeway my speedo says 15MPH and at 50 it says im doing 10. Thought it might be a speedo gear striped at the vss but the gear and the gear in the tranny look real good. Some one told me it might have something to do with the pcm or tps but I can not get a scanner to work on the port. So my question is how do I get the port to work and what else should I try its driving me crazy!!!!!!!! The odometer and trip meter both work but real slow like it is matching the speed that is registering. not sure what to do next any insite would be awesome.

PLEASE HELP ME BEFORE I GO NUTZ! Thanks

IF you could PM me that would be great to. Thanks

Injuneer

Need specific info on the vehicle - year, model, engine, trans and any major mods. Best thing to do is enter a "Signature", so that info is always appended to all your posts.

You mention OBD-I, but in the 4th Gens, at least with the V8 models, there are different issues with scanning the 93, 94 and 95. On the other hand, only the 93 has a VSS with a driven gear. 94/95 have a magnet reading a reluctor gear. That's why we need specific info on the car.

Has the vehicle had a trans swap? If you swapped out a 4L60E for a T56 and did not update the PCM to the T56 program, your speedo would read low by a factor of almost 1:2.5

Injuneer

I thought this looked familiar.

https://www.camaroz28.com/forums/gen...issues-870027/

Best thing to do, rather than start a new thread, is to push your original thread to the top with a new post, and the message "TTT"..... "To The Top". You can do that no more than once every 24 hours.

chevyman1217

Its a 1994 camaro with a 3.4L t-5 5speed not sure if the tranny has ever been swapped and it has a gear in side the VSS just like a 1993 I thought it was suppose to be that way but if it is only that way in a 93 maybe they changed the tranny and used one out of a 93. not sure I have only had the car a few weeks. I haven't done any mods yet want to get this problem fixed first.

chevyman1217

would the abs inop light being on have anything to do with the speedo not working? It has also been on since I got the car. any ideas?

Injuneer

My comments about the gear driven VSS in the 93 trans applied to the 93 LT1 engine/trans. Since I didn't know what your car was, I was simply pointing out the importance of providing that ino up front. I don't know anything at all about the VSS used with the T5 in the V6 cars.

bobdec

The ''94 3.4L (L32) uses a reluctor and magnetic pickup similar to the 5.7L (LT1). The VSS feeds the PCM and the signal is converted to 4K pulses per mile similar to the LT1. I have not been able to find the number of VSS pulses per revolution for a T5. If you sensor is gear driven it's from something other than a '94.