I have been fighting this for 5 months two shops and 200 bucks and still no clue

Problem 1993 m6 220k stock

I have no cruise no trip/od and obviously no speedo

What I have done other than waste 200 bucks to get same answer " I don't know"

I jacked car up and turned wheels and tail shaft gear is turning
I cut wires from vss to PCM replaced it with 14g wire twisted and solder and double shrink wrapped it
Power blue/white to cluster was confirmed and when I turn key the speedo needle does power up
Yes vss was replaced 3x. Still have all three brand new in box

Only code is 24 which is vss circuit failure or something like that

So could this actually be a computer problem?

Yes cluster is a 93 (yellow needle 150 mph)

I really need help here and also will a auto computer work cause I have located one

 

The VSS feeds the ECM and then the ECM converts the VSS AC signal to a pulse signal and sends it to the speedometer. DTC 24 says the ECM did not see a signal from the VSS (+/- 15V AC sine wave) for at least 6 seconds. Pull the VSS connector off the transmission w/key on and engine off verify you have +5v between the two connector ends (+VSS wire (yellow on my '94) and - VSS) going to the ECM. That verifies the wires are going to the ECM and the ECM is putting out the +5v reference voltage. You can also check for resistance across the VSS sensor pins on the transmission end, but since you are on VSS number 3 that does not seem like your problem. Since you have not changed anything prior to the failure (ECM, or code loads). If you have +5 (wires and ECM connection good) and a good VSS sensor the only other cause could be a bad ECM (very rare) or something messed up in the reluctor in the tailshaft (again very rear). If you ever go to a shop again for this problem make sure they have the correct GM test equipment. They s/b able to verify if the VSS signal is good to ECM and then they can inject inject a test VSS signal into the ECM to verify the ECM is good.
I do not know what a 'auto computer' is so I can't comment on that ..

 

Some of the 93's are different. They send the VSS in parallel to the ECM, the speedo and the cruise. I can't remember whether its the M6's or the A4's, since that appears to be what determines the setup. The ones that feed directly to the speedo have a gear driven VSS, so that you have to change the drive and/or driven gears to adjust for tire diameter and final gear ratio.

 

And the reason I know that is because of a previous thread. When I "searched" for the thread, I see it was the same vehicle, and we established there that it's the A4's the feed the speedo direct from the VSS.

https://www.camaroz28.com/forums/sho...d.php?t=812024

Ignore previous post.

 

I converted my 93 to a 94 ecm and im swapping my dash and cluster to a 95 ta wit 15k on it. If all doesnt go well for you ill sell you my 93 m6 pcm and cluster wit 86k after I do my swap. If your interested....

 

Yes I would!

I ordered a vss pigtail just to eliminate that as well.

I could have a bad cluster I guess if the ground on it determines the vss signal, but I was rationalizing between not having cruise control as a means of computer getting signal and not cluster. I guess my question about the auto computer was if I could swap EPROMs but that might be bad in mine. Im not ruling out my ecu cause it's a remanufacture not factory

 

Fred yes I know this has become a pita when 3 shops 50 bucks a piece give me no help let alone do no more than what I have done it gets really frustrating

 

Ok well see what the pigtail does and let me know what u wana do. There a whole t56 harness on ebay for 120 I think, thats it you wana replace th whole thing

 

I'm about ready to convert this puppy to 94 and up since I can get everything and cheaper lol. The 93 stuff is like a lost relic

I'm just scared of the harness looks to be a pita

 

Madtuner replied back to me saying on 93 models he has seen this as a common failure so I'm getting mine rebuilt and updated tune

 

Back to Fred's post #3 , thanks for that info... at first I thought all '93 's fed the VSS to a buffer box that bypassed the ECM and fed the speedometer/cruise, and required physical gear change or a Dakota converter box to calibrate speed. Then I read other info that the VSS feeds the ECM similar to the '94's and up and you could program the chip. W/O a '93 service manual I can't really pin down the actual answer. I was working with a poster with a Jag LT1 w/'94 harness and PCM conversion. He then installed a 93 M6 into the '94 PCM and loaded '94 M6 PCM code. The VSS origionally worked with a 4L60E setup but when he converted to a '93 M6 , no more VSS speed showing up in the '94 PCM. Think I totally confused him and myself. Would be nice to get this cleared up. To you '93 tuners..does a '93 TunerCat definition file allow speedometer changes ?