Whacky Speedo!!!

[1992ToronadoGuy]

Ok, this has been going on forever.

The speedo on my 92 Riv doesn't work, and usually reads 0 MPH when I'm driving, or parked. But once in a while, it starts to go bonkers and tells me I'm doing 100 MPH when I'm parked or 15 MPH when I'm on the freeway. It is always some random number. Then, even more rarely, it works properly ( usually when I first get on the road. )

The next weird thing is that the cruise control works perfectly, and knows the right speed, even if the cluster is going whacko.

I have replaced these things so far, to no avail:

1) Gauge cluster ( twice )

2) Speed sensor ( twice )

3) Cleaned the cluster connector

I also get no diagnostic codes.

Any ideas?

[padgett]

Get a scan tool and see what it says. Any chance you have the wrong MemCal ? (Harry had something similar going on about a years ago after swapping ECMs).

[Barney Eaton]

Since you have done the things that come to mind first, now you must determine where the problem resides.

The signal comes from the sensor, through a cable to the ECM (engine control module) through a cable to the BCM (body control module), through a cable to the instrument cluster.

Since the engine runs ok, since you did not mention any problems, then the problem could be in the BCM or cables.

Go to section 8D of the service manual (can be seen on line at www.reatta.net)

and you can run diagnostics. First you can varify the vehicle speed at the ECM, with the help of a co-pilot you can drive and take readings, then switch to the BCM and see if it is getting correct readings.

This will help you get closer to finding exactly where the problem lies.

[Jim]

Barney,

I have both an '89 and a '90 service manual so I have never needed to use the online service manuals. After reading this post I thought I would try and look at one on line. I went to www.reatta.net but couldn't find the link to the service manuals. Where is it? I did go to "links" on the left side and then clicked on "Reatta/Riviera service manuals and that took me to some computer dating service.

Someone may want to check this out and get rid of the dating service but in the mean time, how does a person get to view the online service manuals?

[Guest Greg Ross]

Intermittants are a pain!

When I installed the calibrator to correct VSS output for my 5-Spd. transmission I cut into wiring at the BCM/ behind the glove box. If all else is working I'd proceed connector to connector cleaning and exercising. You didn't mention how long you've had this going on, is it something new, something the car came with?