Hey folks,I`m new to this site.I have a 92 rs camaro 25th ann edition and the speedo works once and a blue moon...I`ve replaced the VSS sensor thinking it was the problem but it was not.I`m not sure what the problem is now,ANY INFO WOULD BE GREAT FROM YOU GUYS...THANKS

 

If it's a TBI engine, you have a VSS buffer box somewhere in the car (somebody please chime in). It is powered from the gauge fuse so it should have power but also check its ground. It might have gone bad.

Lou

 

It's not a TBI engine, it's an MPI engine, 3.1 liter motor. Thanks for the response Lou. Above is the motor that I have. Anymore info or help on this is GREATLY appreciated!

 

If you replaced the sensor, the only three other components left in the system are the ECM, wiring and the dash. Any of these can be bad.

Important question: does your cruise control work? Or only once in blue moon? That would tell us where to look for the fault.

How savvy are you with wiring and testing? Do you have a voltmeter and know how to use it? Can it measure resistance and frequency?

This is a diagram that you'd want to use to check the VSS signal path.
http://www.austinthirdgen.org/mkport...F_and_vin8.jpg

Please answer the questions above and we'll take it from there.
Lou

 

Members of my family drove it so I do not know how it was treated, driven, etc...The car has been parked in my garage for around 2 years. It drives good, there is just some things that has quit working at the moment.

1-Cruise Control-did not work, then it started working and has been working ever since.

2-I am so-so on the wiring issues and the I have a voltmeter. I do know how to use it but I am not sure of the resistance and frequency. Definitely not an expert.

Hope this information helps you out to help me out with my problems. Thanks again Lou!

 

Alright, that's some good info.
If cruise control works, that means that your VSS signal is getting to the ECM. So it must be either the dash instrument or the wiring between the ECM and the dash.

You can test your speedometer easily. You can remove it from the dash (if you've never done it, follow the repair manual, it will tell you exactly how) and once it is out, look at the pins at the back. This picture will help: http://www.austinthirdgen.org/mkport...ter_pinout.jpg
You'll be working with the connector on the driver side of the instrument cluster (the one behind the speedometer). Locate pin #2 and put ground on it. Locate pin #14 and put 12V on it. Then locate pin #1 and attach a wire to it. You will need a rasp or file. Ground the rasp/file and then take the wire from pin #1 and run it over the rasp/file at a decent speed. The speedometer should jump significantly. That will tell you that the speedometer is good.

If the speedometer fails this test, you'll need to replace it. I have a few if you need.

Let us know.
Lou
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If it's not easy for you to hook up all these wires that I just mentioned, you can leave the cluster in the dash but you would still need to locate the brown wire behind the instrument cluster (coming out of the DRIVER side connector), tap into it with another wire and do the rasp trick again (with the ignition on). It's not easy to get to those wires up there from underneath but you might prefer this to pulling the instrument cluster.

Lou

P.S.: You can put your vehicle/engine info in your profile. That way it will be visible to us whenever we see your post. It helps.

 

Lou, Thanks for the info. I will definitely try this to see. I won't be able to try it in the next couple of days but when I do, I will let you know the outcome. Please keep a check on this post for my reply/outcome. Again, thank you!!

 

kinda sounds like i have the same problems that all of you have. not sure though. my 86 iroc tpi surges in just about ANY cruising speed 30,40,50 mph etc. etc. but once i give it a little bit of throttle it smooths out. i let off the throttle and it surges while my 700r4 downshifts. when i take off from a stop the trans shifts fine until cruising speed. then it seems like the overdrive is slipping but its NOT. would this vss sensor cause my converter maybe not engage in proper lock up as well??? please help thanks

 

Hey Lou, would you happen to have a diagram like that for a 305 tpi 86 trans am. I have been looking for one, and I can't find one.

 

No. Your car has a cable driven speedo. I think there is a sticky in the faq board or a tech article about speedo cables jumping. as far as your shifting issues I would first start by adjusting the tv cable, there is a tech article about how to do that. Also check the fluid.

 

tv cable??

 

I think he meant the TB kickdown cable.

Lou
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Sorry, I don't. These actually don't exist anywhere, I had to pull my cluster out and reference every single pin on the connectors to create the pinout diagram myself. You can do the same on yours, it's not that hard.

Lou

 

I think it is the same thing I just meant the tv detent cable. Here is a link to the tech article.

https://www.thirdgen.org/detent

 

Ah, I see. Never heard the TV term, only TB.
They have multiple names for everything, the learning never stops.

Lou

 

was wondering why mine is different? It has a gray wire intstead of a brown? do you know why?

 

Short answer: because it's a Cheby.

Longer answer: VIN E (TBI) has a brown wire, VINs T,F,8 (MPFI) have a grey wire. Or at least that's what GM claims (don't hold your breath).

Hope this helps.
Lou

 

thanks

 

hmm just wanna point out since i dont think anyone mentioned it but depending on tbi r tpi..cable and elect speedo..speedo gear in the tranny could nicely be melted down mine was! all that testing lead me back at the tranny looking for a damn gear..after buying another buffer box and sensor,testing the guage and ecm etc etc.Take a quick look at that if you can.

 

The original poster said that he replaced the VSS and it didn't help. We covered that.
Or are you talking about another poster?

Lou