Hi, I recently bought a 1990 Trans Am (lb9, t5) and have been working to get it up to tune as a first priority. The car keeps throwing me a code 24, which according to http://www.austinthirdgen.org/index.php?pid=27#5LTPI as well as the link here on TGO, is what sounds like a tps issue but everything I only comes up with it being a vss trouble code. The code does only come on at low speeds.

The car does have a vss issue, the previous owner acquired it without a transmission, put one out of an '85 in it and due to the '90 being an electronic vss and the '85 being mechanical, ended up putting a vss out of a
'94 in it(thats what he said, I wouldnt have figured it would fit). The speedo comes to life around 20mph+ and quickly accelerates to around 20 -30 mph so it does seem IMO that it is a pulsing issue and not a gear issue.

I have a new t5 vss to throw in it but in the meantime, should I be looking at tps issues or is the code list I linked incorrect and code 24 is a general vss/tps code? Its hard to determine based on when it throws since it is only on occasion and at low ground and engine speeds that would match either possibility.

 

Thats odd from what i know code 24 is a VSS issue not a TPS. Perhaps that web site is in error? I think your biggest problem is the fact you have a 94 vss sender in it. If i recall correctly they used a different PPM count than a factory 90s sender.

 

According to my shop manual, a code 24 is VSS related.

JamesC