Bouncing VDO Speedometer ??? ***VIDEO***

[The_Six]

I hope it doesnt take me that long to do. Good luck with the job hunt I lost mine for about a month and my wife is going on 2 now so I know how bad it sucks. Luckly I got a new job before we had to start selling body parts.

 

[The_Six]

Hope you don’t mind me continuing your thread, I’m working on this again myself now and I’m not sure ware to start. I have moved the sensor to the trans and hope that fixes the bouncing my engine is out so will not know until its back in. What I’m working on now is the cruise control and VSS signal to the ECM. My car had the AVC dash put in it by the previous owner and I have never had a VSS signal to the ECM if you look on my scan master it just says 0. My tach works great so I’m going to order 1 Caspers conversion module, and 1 tach module other than that all I need is wire , I’m trying to figure out why I have never had a VSS signal to the ECM. My car has had some of the original wiring cut up all the idiot lights have been cut off. I’m going to check the factory VSS buffer today when I get off work to see if it is even there or connected to anything. I’ll take pics of what I find.

 

[tonysmach]

Looking for help

It really wasn't that bad...

The best way to do it is to mount the sender on the trans to eliminate the cables. MAKE SURE you have positive engagement between the sender and the speedo gear. That was a setback for me... as I was looking for an electrical problem. It was a simple fix, but one that could have been avoided if I had known to look for it.

You will need the Caspers conversion module to convert the VDO 16-pulse signal to a 2-pulse signal. For the cruise to work, you will need a "tach" module also. (This would be #2 if you already run one for a VDO tach.)
Ignore the "Tach Module" name... it's needed to run the cruise control.

When you unplug the factory VSS buffer (little green box) you will see a white plug with 3 wires and a black plug with one wire.
The brown wire in the white plug goes directly to the A10 terminal on the ECM and gets connected to the signal output from the conversion module. The wire in the black plug goes to the cruise module and gets connected to the signal output from the tach module.
Both the signal converter and tach module each get 12V+ switched, a ground, and a signal (in) wire from the VSS sender. The only outputs from them are the brown wire from the signal converter (going to A10) and the yellow wire from the tach module (going to the cruise module).

I wiretied the two modules together and made a harness to keep it clean and the wires color coordinated.

Here's a couple pics:

I followed this procedure but I am getting a malfunction code 24 - VSS sender bad. I connected my VSS conversion module and tach module with a T-tap. I could not get to the wires without removing the radio. Was I suppose to remove the VSS buffer (green box). Is that why I am getting a MAL code 24?

 

[The_Six]

yes defenitly remove the old green box. Were did you tap in to the wires at ? you should have tapped in to the wires that would have been pluged in to the green box. you dont want that box trying to feed a signal to the ECM now. Its no longer getting a signal from the speedo so even if your green box VSS is still good it will not be seeing a signal from the speedo and could be causing the code 24 .

 

[tonysmach]

yes defenitly remove the old green box. Were did you tap in to the wires at ? you should have tapped in to the wires that would have been pluged in to the green box. you dont want that box trying to feed a signal to the ECM now. Its no longer getting a signal from the speedo so even if your green box VSS is still good it will not be seeing a signal from the speedo and could be causing the code 24 .

OK. I will try to remove the green box this weekend. Thanks.

 

[jooset]

Speedometer still not right, cruise inop too.

First of all, this was an awesome thread and really helped me with my recent installation. I have Performance Industries GNX 'style' dash, in the car and working for years. Haven't done anything to anything remotely close to the dash or the speedometer or the vss. Speedometer started going wacky on me few weeks back, working when cold, then after driving a few minutes, fluctuating, more and more, then wildly, then indicating zero (and it wasn't my driving ). Oh yeah...and the scanmaster mph was jacked up similarly. I only have a lower speedometer cable which runs from the tranny to the vss next to the powermaster, from there it's just a wire (pair) that goes into the dash and electic VDO speedometer. I started by lubing the lower cable - no difference. I replaced the lower cable - no difference. Took a guess that it might be the VSS. So I decided to try a new one. So I purchased the three CASPER's boxes reference by so many (102046 VSS CONVERTER MODULE, 102007 VDO TACH CONVERTER MODULE (for the cruise control signal), 102045 VSS VDO Sender Dead End)...and spent the weekend rewiring.

Wired it in accordance with: http://www.installationinstructions.com/102046.pdf except that I didn't run black and red to the speedometer (because it is already powered and grounded as part of the wiring in my GNX cluster).

Now, after a test run...I have just minor, but annoying fluctuations on the speedometer (+/- 7mph) and rock steady mph on the scanmaster....and my cruise doesn't work. So now I'm guessing that my speedometer is bad? Not sure why cruise isn't working. Any ideas?

Also, I assume, though it doesn't say explicitly in the wiring directions, that I can use the red and the black that used to connect the speed buffer (green box) to source the new boxes. (i.e. where the wiring diagram says "connect to switched +12Vdc").

whew! appreciate any suggestions.
Matt

 

[jooset]

drove it to work today...i should note that the fluctuations are worse at the lower speeds (<40mph) now...actually not too bad above 40. cruise still inop.

 

[jooset]

rewired with the VSS attached directly to transmission

Redid my installation, with the VSS attached to the transmission. Everything works like a champ...except cruise control (which was working fine before the installation). I checked the switch on the brake pedal and all the vacuum lines (just in case I bumped something) and it looks fine. Not throwing any codes. Cruise just inop.

 

[we4Mateo]

Revive! Old thread back at it. Why can't a Casper's conversion module not feed a two pulse signal to the VSS buffer? Seems like there would be less wiring; or does the buffer need a different signal?