Community Forums

RayChez1 · 01-13-2022, 07:19 PM

Last week while driving from Las Vegas to California I stopped at Flying J truck stop in Prim Nev to fuel up. When I left there I noticed that the speedometer was not working proper. I got on I-15 and that is when I noticed my speedometer was only showing that I was doing about thirty miles per hour when I knew I was doing more like sixty miles per hour. Now my question is, does the ignition switch have anything to do with the speedometer? Reason I wonder about the ignition switch is because my wife forgot the engine was still running and could not hear the sound of the Cat engine which is loud anyways, but with all the big rigs fueling she did not know the switch was in the one position and could not pull the key off. I needed the keys to unlock the cover outside to fuel. Anyways she finally figured it out and handed me the keys, but I was wondering if the pulling hard of the key at the ignition switch might have had some cause for the problem with the speedometer. I just kept driving and did not stop anymore until I got home, so I am not sure if the problem is gone now knowing the switch might be working better. NOT SURE!

Skip426 · 01-14-2022, 09:36 AM

I have to ask if the transmission is shifting properly and is the read out of the rest of the gauges appear normal ?

Your gauge package testing should be covered in this first pdf and checking the Allison controller for codes related to the output speed sensor ( where the speedo gets it's info).

PaulTNaples · 01-19-2022, 03:59 PM

What was your rpm reading? If you have a gps, why was the speed indicator reading? Those can help you start to diagnose the issue or at least to give clues to the repair shop. Hint…could be the speedo gear on the transmission.

RayChez1 · 01-19-2022, 11:12 PM

The transmission was shifting good, no problems there. I had this problem happen before, but it corrected itself. I just stopped the first time it happened and then took off again and it worked fine until a few days ago. I have not driven it since I got back, but I have a feeling that it will work again. The tach worked just fine, no problems there.