NEED HELP Speedometer not working/hesitation

Seirra97

Original poster
Member
Aug 19, 2020
3
Wilkes-Barre PA
I have been have some issues with my truck and I want to see if its a major money fix or not. The speedometer and the odometer are not working as well as the truck has been driving real hesitant starting off. My girlfriends father (mechanic for 30+ years) hooked it up to his computer and it says its the ignition switch. And my Cousin Hooked it up and said there is and issue in the Transmission itself and it most likely would need to be rebuilt. I need help as anybody else run into an issue like this and what did you do.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
It sounds like the VSS (vehicle speed sensor) is not working. Thats a relatively easy, and cheap fix. Is it guaranteed to fix it? No. But I would throw a 35 dollar part at it first, before throwing a 2600 dollar tranny at it.

The way you can tell if it is the Ignition switch is by turning on the key, and watching those 2 gauges, turn on the key. They both should drop to below the -0- line, and come back to zero. If it moves like I described, I doubt its the ignition switch. Usually when an ignition switch goes bad, you end up with a myriad set of problems. Not just ones related to one thing. If you are still in doubt, its a really easy fix, and a 70 dollar part. We only recommend ACDelco or Delphi parts for this.
 
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Seirra97

Original poster
Member
Aug 19, 2020
3
Wilkes-Barre PA
It sounds like the VSS (vehicle speed sensor) is not working. Thats a relatively easy, and cheap fix. Is it guaranteed to fix it? No. But I would throw a 35 dollar part at it first, before throwing a 2600 dollar tranny at it.

The way you can tell if it is the Ignition switch is by turning on the key, and watching those 2 gauges, turn on the key. They both should drop to below the -0- line, and come back to zero. If it moves like I described, I doubt its the ignition switch. Usually when an ignition switch goes bad, you end up with a myriad set of problems. Not just ones related to one thing. If you are still in doubt, its a really easy fix, and a 70 dollar part. We only recommend ACDelco or Delphi parts for this.
Neither one of the needles move when I turn the key on
 

christo829

Member
Dec 7, 2011
497
Fairfax, Virginia
So...crankshaft position sensor / camshaft position sensor correlation problem, which *will* make the truck run poorly:
  • Stalling
  • Rough idle
  • Difficulty starting
  • Engine misfire above 1500 RPM
That's just a quick general list, and not all inclusive.

Make sure when they're looking these codes up they're actually looking at GM definitions. Other manufacturers have the same P1345 code, but it points to different areas.

Had any work done on it since about the time the problems started? What's the maintenance history on it?

You could just pull the parts shotgun trigger or we could work on troubleshooting. Not sure what your timeframe is on repair. Also, if you replace both sensors at the same time, you may need a relearn. Some vehicles you can set up a relearn yourself. Others need to be hooked up to a computer and commanded to relearn.

It's always possible that the ignition switch is still a factor, but that usually throws a few other weird symptoms.

Good Luck!

Chris
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
Neither one of the needles move when I turn the key on
So now you have to determine if you have a faulty gauge cluster, or a faulty part. The gauge clusters are a very common problem for all of GM. But it could still also be the ignition switch. So now you are in a predicament of figuring out the problem. Clusters run about 120 bucks or so to repair. The ignition switch is a 70 dollar part. Both still need uninstalling, and installation.

The gauge cluster is the easier repair, as you can pull it, and take it in for repair yourself (I dont recommend trying to repair yourself). The ignition switch could also be done by yourself, if you have the technical know how, and tools, to do it.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I think you have two separate issues here. P1345 has nothing to do with the speedo. Has anything been done to either the cam or crank sensors or the timing system or an engine swap? Get your GF's dad try to do a CASE relearn. Might just fix it.

For the speedo and poor shifting, was anything done to the tranny or transfer case? Were the sensors possibly disconnected? I've seen someone replace the tranny and accidentally connected the front and rear transfer case sensors backwards. Again, using the GF's dad's scanner, see if you're getting any speed reading from the PCM. If not and not getting any code for a speed sensor, try swapping the sensor connectors front and back.
 

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