edman87k5

iTrader: (3)

The speedo in my 91 rs 305/5speed did not work when I got in it the other day. It did not move, just stayed on 0. While cruising, it will occasionally jump up and read for a few seconds, then fall back to 0. I pulled the vss, expecting it to be a pickup for a tone ring that needed cleaning- wrong. I have no experience with this type of system. I have searched on here and read several pages of posts of different problems.
From what I understand, there is no voltage sent to the vss. One of the 2 wires is for speedo, the other is for cruise. Is this correct?
I hate to spend $70+ on a vss and that not be the problem.
Any help is appreciated, thanks.

kaptinkafeen

iTrader: (2)

You mentioned that you pulled the vss - and the connector was clean, what about looking at the vss buffer under the dash - check that connection as well, followed by the main connection on the back of the dash pod. Seeing that it is an intermitent problem, this would be one of the first area to look at - lose connections at all the possible locations. Following this step, yet related, check you grounds.
(maybe somewhere in the car's life someone tampered with wiring under the dash - a sound system or alarm instal perhaps)

At the vss buffer the following colour codes apply - purple and yellow are FROM the vss to the vss buffer, pink with black stripe - 12V power, brown - not used, green with black stripe - this goes to speedo, black with white stripe - ground. (do a seatch for vss buffer - there are some great pics to illustrate this) The two wires that run off the vss send a signal to the ECM or in your case the VSS buffer - it is from here that your cruise control gets its info.
Now from what I understand, ( I have a '91) the colour of the speedo signal wire (green with black stripe) may be different from year to model year (not sure), and moreover, its pin location at the dash pod connection may vary also, but these are minor differences. (again, I am not sure about this) Failing this, I would suspect that the electric speedo motor mechanism may be on its way out - how many km's on the dash gauges? Checking the VSS buffer is easy, but to get at the dash pod connector can take some time. I had a '92 with an irratic speedo - turned out to be the actual gauge was wearing out. Maybe you could also check the vss by swapping in a doner or loaner - it's also an easy R&R.
-Andrew

edman87k5

iTrader: (3)

Thanks for the info. I won't have a chance to mess with it for a few days, then I am going to hook my buddy's scanner to it and see if I am getting any kind of signal from the vss. I have to hook up the scanner anyway to set the pot I installed on the tach board. I just talked to my bud and h says he can find the problem- it is nice to have a close friend that is a mechanic with all the cool toys.
I too am thinking a bad connection or bad failing vss. It has not worked at all the last 3 times I drove it. I just didn't want to start throwing new parts at the problem and I don't know anyone else with a 3rd gen.

92 Heritage RS

I had the same problem in my ,92. It turned out in my case that the speedo itself was dead. Our's is an electronic speedometer. I replaced the VSS sending unit originally, but to no avail. Then I went to the junk yard and carefully removed the speedo from a donor. I had to switch the odometer and trip spools (The donor had higher miles on it!) which required the complete disassembly of the unit. But when I installed it it worked perfectly. Like I said mine had the exact same thing happen, first my odometer stopped working and then the needle would jump up and down and then it quit all together. I hope this helps!

Ravenant

The speedo in my 91 has also been acting odd, but along with the speedo going my AC also went out. For the past few days though, the speedo will run for a while and then crap out after I've driven for a little bit.

Wadebryant

The two common problem area's that I've had were found at the male to female connection at the cluster and at the connection to the vss. Both not being secure. Might also, test the vss with an ohm meter to make sure it's in working order.

If there's a bad connection, the speedo may work then quit...repeat this cycle when you hit a bump or make a turn etc....

If the ecm isnt throwing a code 24 (?) - missing vss - then, I'd look for a short circuit to the cluster.