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I have a 1989 Camaro RS 305TBI 700R4. Speedo is cable driven.
When I got the car around 6 months ago, the speedometer worked.
Suddenly it stopped working, and now I get a SES for VSS, to be expected.
I got a brand new GM genuine cable, changed it. Before doing so, I spun the speedo head on the back of the speedo to see that it still reacted, it did.
to my surprise on test drive, it still does not work.
With the old cable out of the car, I spun one end by hand and sure enough, the other end spins. i.e. there was nothing wrong with the old cable.
I have a driven gear sitting on my workbench that I purchased to make the speedo accurate, before this happened (as this car has different sized rims on it). I havent touched it since the speedo broke.
Am I correct that, since its mechanical, the likely culprit at this point is the drive or driven gear? Do we see these going bad?
Second question: from everything I have read a 1989 its hit or miss if it has a VSS on the transmission, or a speedo cable.
Mine clearly has a speedo cable, but I noticed while down there that there is very clearly the wiring harness for the VSS right where it would need to land to go to the VSS at the side of the tailshaft.
On cars that use this VSS, is the speedometer electronic? Are there electronic speedometers that are NOT the 90-92 cluster?
What does this wiring harness being present, but unused on my car tell you? My car previously had a VSS maybe?
My cluster has the yellow buffer box on the back of it. I have to assume that it all worked as is wiring wise to the ECM bc I did not get the SES light until the cable broke, but it was very soon after acquiring the car. I have win ALDL to see if the ECM is getting speed signal once I get the speedo turning.
My main concern is that someone swapped the cluster and trans/speedo housing out, and the ECM will still throw the SES code. If anyone can clarify what a non speedo cable VSS 89 cluster looks like / works like, id really appreciate it.
"Suddenly it stopped working, and now I get a SES for VSS, to be expected."
So there was no VSS SES light on prior when the speedometer was working?
Then it would seem that the car was happy the way it was with a mechanical cable vs an electronic sender.
Step #1: Make sure the cable is fully seated and locked into the speedo head with it's clip 100%.
Beyond that you'll either need to remove the cable at the speedo and spin the trans to see if the cable end is moving, or disconnect the cable at the trans and spin it with a drill to see if the speedo moves.
Hello
I am going to ignore the electronic part of this question for now, and stick just to getting the mechanical speedo to turn.
So I went back into this today and have some updates, although it still does not work. Emphasis on driven and drive for my own sanity and yours lol
The speedo does work, and moves when attached to a drill at the end where it connects to the transmission
With the DRIVEN gear housing removed, I tested the old DRIVEN gear in the housing mocked up to the old removed (and still working) speedo cable, it turns the cable as does the new gear
I inspected the part of the DRIVE gear that I could see from the hole left by the removed driven gear housing. It looks OK, but cant see the entire thing
When put back together with a new DRIVEN gear, it still does not work
Is it safe to assume that the issue HAS to be with the DRIVE gear on the tailshaft?
I don't own any 700r4...do they all come with this gaping hole for the speedo...use your imagination as to get it in view to see the clip...or just try rotating it on the output shaft.
...example of what you don't want to see...but then again depends how you look at, smoking guns can be a good thing.
Last edited by stew'86MCSS396; Dec 28, 2024 at 08:01 PM.
Yes mine does look like that. If the clip is not sitting in there like that, which I do not believe it is. Would there be any other way to tell. IE what is the failure that the clip being off causes? the gear to move? etc? Because i can easily put a finger on that gear and see if its loose.
Thanks for the guidance
edit: i think you are saying that the clip spins with the gear, naturally. So i should spin the tires with the wheels off the ground in N to see if i can get eyes on the clip through the hole? THanks
Yes mine does look like that. If the clip is not sitting in there like that, which I do not believe it is. Would there be any other way to tell. IE what is the failure that the clip being off causes? the gear to move? etc? Because i can easily put a finger on that gear and see if its loose.
Thanks for the guidance
edit: i think you are saying that the clip spins with the gear, naturally. So i should spin the tires with the wheels off the ground in N to see if i can get eyes on the clip through the hole? THanks
You got it
Reach your finger into the hole, and see if you can turn the gear without the tailshaft moving. If the clip is there, you won't be able to turn the gear without the tailshaft wanting to be turning with it. If you can turn the gear, without the tailshaft wanting to turn with it, the clip has fallen out.
Last edited by OrangeBird; Dec 29, 2024 at 09:30 AM.
Reason: clarify my point ;)
So the drive gear does not turn by my finger, but i felt around inside and low and behold:
Looks like you both were right on the money. I imagine that it does spin freely when under engine power.
I am going to make an appointment for a trans shop to pop the cover and get this sorted for me. Thanks. if you know anything about speedo calibration I am going to make another post to check my arithmetic so I can fix this once and for all.
Thank you SO much for your expertise. Great job, Nailed it!
Is there any way to get this clip back on without taking the tailshaft cover off? I rotated with the car in neutral and can see where its supposed to slide in ? is that a crap shoot to try?
I had the drive gear swapped out with a new one and a new clip as the clip was actually broken. The speedo does turn now, but it seems i still have the wrong driven gear for my setup. If you know anything about that please see my other post to help thanks for the help here
