digital dash in 1984 Riv

[Booreatta]

I was taking the Riv back to the tranny shop today and the speedo was not working. It is the digital dash for speedometer and fuel. The fuel guage is working I think but the speed jumps from 0 to around 38 then back to 20 with in a few seconds. I think it most likely the digital part but could it be related to the tranny issues. Where is the pick up for speed. Thanks Chuck

[Rivieraman]

I would bet it is not the digital dash. I bet it is the cable from the trans.

[Guest pfloro]

Chuck:

Since your '84 Riviera has a mechanical odometer, there is a speedo cable routed from the trans through the firewall to the cluster. The VSS (vehicle speed sensor) is mounted behind the cluster. It's o/p feeds the digital speedometer either directly or through the ECM. The ECM needs VSS i/p for it's computations. If the VSS was bad, you would probably be seeing a check engine light. However, since it's an intermittent problem, the ECM might not 'catch' it. OBD I was very slow & not too intelligent (However, very sophisticated for it's time).

I would 'flash out' the ECM trouble codes thru the ALDL to see if a code 24 exists. A code '24' indicates a problem in the VSS circuit (open circuit or no activity).

I suspect the problem is in the digital cluster itself. I found the following site which should be able to repair it. Nationwide Speedometer and Instrument Cluster Repair . I have not used them but they 'appear' competent.

Keep us posted on your 325-4L too!

Paul

Edited August 19, 2010 by pfloro (see edit history)

[sosuzguy]

Chuck an ROA member in California recently contact me with a similar problem. He said his digital cluster had went out and was sent off to some shop for repair. They called him back and said the CPU for his cluster was out which made the number roll, similar to what your describing they would go from 0 to 25 then 34 then 46... The shop that had his cluster could not fix it. I suggested he call John Spina at Casper's Electronics as they repair all of these clusters for the GN's. John knew exactly what was wrong and the member shipped his cluster to them. CEI - Casper's Electronics, Inc.

[Booreatta]

Once again I thank everybody for your help. I took the Riv over to the tranny shop again and I told him to keep the car for however long it takes to get the tranny right. I have printed off all of the information that I was able to find and all of the posts here on the forum. He should have enough information to fix it. He is also going to check the speedo to see if it is the cable or just a faulty digital unit. I will keep everybody posted and I will keep my fingers crossed

Thanks for your imput

Chuck Kerls

booreatta@cox.net