2000 Silverado VSS

Hey everyone, I have been having problems with my speedometer and odometer (2000 Silverado 4.3 automatic 4X4) both work every now and then...
I tried a a different cluster same problem.
I finally brought the truck to the Chev dealer after one hour and a half the guy still has not found the problem. He says it might be the VSS but he wants to check all of the wiring from the VSS to the cluster.
He did check the wires from the VSS to the computer under the hood they were ok, now he wants to leave the computer and check the wiring towards the cluster.
Should I just go ahead and buy a new VSS before I go back to the dealer. He did not really tell me if a VSS could be tested or not. He did test the cluster with the GM computer thing and it seems ok.
He did alot of other test also.
He had the wheels lifted, the truck in gear and the computer was able to read the speed does that mean the VSS is good, the guy was unable to tell me.
I should mention that this truck has been restored it was flooded.
I am just worried that once the dealer found out this was a rebuilt truck they wanted to play around and say it is a wiring problem. The truck ran at least 6 months before this problem
Thanks a million
nevlis
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Checking wires sounds like the right troible shooting to me. Intermitant problems can be hard to trace.
Knowing it is a flood vehical makes a differance. It tells the tech what sort of things he should look for. Flood vehicals are prone to electirac problems from gounding points rusting. There can also be damaged wires that only short out under cirtaint condishions.
I would go back, let them check the rest of the wires. They have the proper tools, and the proper books. Ask them how they test the VSS. Charles
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Thanks for the reply... However, before I back I think I will stick in a used VSS that my friend has and try that.
Thanks
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If the computer can see the vss signal but the cluster cannot, then the vss is not the problem. They sound like they're doing a fine diagnostic job. I am curious, however, if the vss sends the signal to the pcm, which in turn sends it to the cluster, why it was necessary to check the vss or wiring to the PCM, since all those items seem to be verifiably ok due to the PCM seeing the vss signal. Then again, I can't remember how this circuit is laid out, either.
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silven wrote:

Look closely at the VSS you take off. Do the connections look oxidized or corroded? If so, it may have been a connection problem due to corrosion at the VSS connector from the flood damage.
Bob
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Thanks everyone, The connection to the VSS looked good he also tested the wires from the VSS to the main computer under the hood and everything seems ok. I guess I will let him continue his work from the main computer to the cluster. He also connected his multimeter to the VSS but was unable to determine anything from that.
What I want to know is how come he was able to control the speedometer with his gm computer... Does the gm computer pass through the main truck computer under the hood? If so does that not mean that I have good wiring going through?
Thanks everyone
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Would someone know which wires I should follow from the main computer to the cluster for the speedometer... since it will be another week before my next appointment... maybe I can check things out a little on my own.
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There's probably a speed output from the PCM to the IPC (Cluster). You'd need a schematic to determine which wires these would be. Unfortunately, I no longer have access to one.
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The tech 2 communicates directly with the cluster, so it can operate the speedometer that way. His test showed that the data bus and that the cluster were working correctly at the time of the test.
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Thanks for the post..
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If you are sure that the cluster you tried is good, the it is probably the connection between the pcm and the cluster. The pcm would throw a code if it lost the vss signal. I think it is a green wire. If you have access to a diagram, you will see it is a single wire that feeds the cluster from the pcm. It is best to replace the wire at the pcm and run it to the cluster also cutting it at the cluster. But you must first check the diagram. The cruise runs off this wire as does the module for the seatbelts. You don't want to lose those in the process. But as far as chasing down the exact bad spot, it will cost you time. One question: does the cruise work when the cluster quits? If so and you have a diagram, you can narrow down the problem from after that point to the cluster.I have found people that had a wiring diagram and put a toggle switch on this wire to keep their car under warranty longer. They just turn off the signal at will.Because it doesn't throw a code.

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The cluster is suppose to be good since I tried another and it had the same problem and the GM tech tested it.. and he was able to control it.
Cruise does not work... but that has not been working since I bought the truck and as I mentionned earlied the speedometer did work for awhile. Maybe the cruise not working has something to do with the problem (I thought the cruise switch was finished because it looked a little worn out)..
where would I find such a diagram, GM manuels for this truck? Or is there somewhere a little cheaper. Does the Haynes book have these diagrams? Is there some web-site that might have them on line. Does someone have one that they might be able to email me.
Thanks everyone for your time and posts this is a great place for help..
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same
What schematics do you want? I should be able to wrangle them up for you. From the looks of it you want cruise control, instrument cluster, and the 4.3 Tranny (for the VSS).
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same
Cruise Control is directly related to speedometer funtions. You should have informed the tech the cruise was in-op. Thier may well be a wire short there.
USED factory service manuials can be had reasonibly thru eBay. Charles
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Hey everyone thanks for all your help. I found the problem
The problem was a bad connection to the Cruise Control module under the hood.
Thanks
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Flood reconstructions are funny:
Because what's not wrong electrically, manifests it's self magically every few weeks. The connections continue to oxidize, especially if it was a salt water flood.
If a salt water flood was the case, be prepared for the fenders to fall off in a couple of years too.
My advice, take apart the interior, and use a mile caustic cleaner to soak the electric connectors, then pressure wash them with hot water. Standard practice whenever I did a flood vehicle. (Purple power works great)
Years ago there was nothing on the market, so white vinegar was what we used in a spray bottle on all the connectors.
Refinish King

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