Speedometer reading MUCH too high..

[kennythewelder]

I don't know if that's what's going on here... My '97s speed as reported by the PCM via OBD2 port is generally very close (at least within 5MPH) to what the speedometer reads in both trucks. It sounds to me like someone may have pulled the cluster needles to switch bulbs and not put them back in exactly the right places.

I do know there are stepper motors for all of the gauges speedo included. So could the stepper motor be bad, yes.

 

[df2x4]

I do know there are stepper motors for all of the gauges speedo included. So could the stepper motor be bad, yes.

Could be... But I'd expect either visible jumping around or complete failure to move the needle if that was the case. If the needle sweeps normally I'd think the stepper motor is probably fine.

 

[east302]

OK, a little more information now.... I just connected my little obd2 device that bluetooth connects to my smartphone. When speedometer reads 55mph, odb2 says it's actually going 40.

How does that compare to a gps reading?

Like Kenny mentioned, it may have been flashed for a different tire size - and I think axle ratio is a variable as well but am not sure.

Per GM, a speedometer reading within 4-mph of the OBD reading is within tolerance.

You don’t have a 4.3L do you? Somewhere I heard that those clusters are specific, but it may just be for the tachometer. As for a 96 vs 98, the visible difference is the red redline mark on the 96 but I couldn’t say if there is any electrical difference between a 96 and 97/98 cluster.

For a 98, the VCM outputs to the speedometer. I don’t have a wiring diagram for a 96, but you could get one from alldatadiy.com ($30-something per year subscription) or a factory service manual. Some PDF versions are here, but none for 96.

You must be registered for see images attach

https://www.gmt400.com/threads/88-95-service-manuals.43575/

 

[99escladel31]

any confirmed fix or updates

 

[TSALI137]

Has anyone found a solution to this?
I just had my 97 5.7 k1500 recalibrated when I installed the 0411pcm for a performance engine upgrade. It read dead on with the OEM 100mph speedometer. Then 2weeks later I did the 99-00 Escalade 120mph swap. Now my speedometer is reading anywhere from 5-7mph off below 60 and around 10mph off above 60. Escalade speedo was tested before I purchased it and was said to be working correctly. Has anyone figured out the solution to this or is it just simply take it to a shop and have the PCM/ECU recalibrated?

 

[chris2323]

Has anyone found a solution to this?
I just had my 97 5.7 k1500 recalibrated when I installed the 0411pcm for a performance engine upgrade. It read dead on with the OEM 100mph speedometer. Then 2weeks later I did the 99-00 Escalade 120mph swap. Now my speedometer is reading anywhere from 5-7mph off below 60 and around 10mph off above 60. Escalade speedo was tested before I purchased it and was said to be working correctly. Has anyone figured out the solution to this or is it just simply take it to a shop and have the PCM/ECU recalibrated?

My speedometer is off by the same amount. Havent been able to figure it out. I know its not a gear/tire issue because the correct speed is being reported by the pcm during a scan.

 

[Steviej455]

I just bought a 97 C1500 5-speed. The speedo reads double of what my actual speed is. I’m getting the correct speed output on my scanner and GPS.

 

[Steviej455]

Well solved my issue I swapped out the speedometer circuit board (the circuit board that the speedometer plugs into) from a known good donar. I also swapped out the odometer motor as it was shot (odometer wasn’t working) Not sure if the issue with odometer motor was related to the speedometer issue or not but everything works. FYI If you have a manual cluster you can use the speedometer circuit board from an automatic cluster. The trans indicator lights are not present on a manual circuit board but are for an automatic board. They don’t light up in manual trans applications

 

[chris2323]

Well solved my issue I swapped out the speedometer circuit board (the circuit board that the speedometer plugs into) from a known good donar. I also swapped out the odometer motor as it was shot (odometer wasn’t working) Not sure if the issue with odometer motor was related to the speedometer issue or not but everything works. FYI If you have a manual cluster you can use the speedometer circuit board from an automatic cluster. The trans indicator lights are not present on a manual circuit board but are for an automatic board. They don’t light up in manual trans applications

Good to know. Thanks