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 Wonky Speedo

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Sprocket

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PostSubject: Wonky Speedo   Wed Jul 03, 2013 12:32 am

So on the new OCC, When you start the car, the speedo doesn't work. Other gauges do like tach, oil, etc.
After about 5-10 miles, it starts working, but last night on a sustained highway run it can jump around a bit and I noticed the tach would jump up and down a little, even though the throttle was steady. Thinking the whole cluster is going, or maybe the speed sensor on the diff. ANy other ideas?
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BigBlackBeaSSt

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 12:40 am

I had this happen in a 80's Celebrity Euro-sport Wagon (2.8 ltr).  It would register at 66% of the true speed and then back to normal randomly. Really strange.  It was the computer freaking out. Once in a while it would loose 95% of the power and limp along like it was giving up the ghost, but then run fine 10 minutes later. Replace the PCM and it fixed it.
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Sprocket

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 10:27 am

Hmm, finding a 350 with 3.23 gears ECU will be a lil tricky.
Might start with a cluster swap first I have one of those laying around....
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YachtDriver

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 10:32 am

I had an issue similar to this with a Honda/Sterling. Turned out to be a bad ground. Perhaps check for wonky grounds?
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BigBlackBeaSSt

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 10:37 am

YachtDriver wrote:
I had an issue similar to this with a Honda/Sterling. Turned out to be a bad ground. Perhaps check for wonky grounds?

I agree based on the inconsistency.
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Fred Kiehl

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 11:19 am

The OCC computer does not process the VSS signal. Since the tach, and the speedo are acting up, it would probably be a bad ground/dirty pin, or the electronics board of the cluster module. The circuit board is the same as the RM (either sedan or wagon) and can be swapped. You may have to move a bulb or two for all of the idiot lights to work correctly. I have swapped them, and they are exactly the same. You will even see notices on them for correct lighting in the different models.
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BigBlackBeaSSt

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 11:20 am

You knowledge is amazing Fred.
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Fred Kiehl

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 11:56 am

Thanks, but the reason I know so much is because I have two OCCs, and if one did not have the problem, the other did. The few things I have not had to fix were experienced by others, and I try to learn from other's experience as well.
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Sprocket

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 2:00 pm

I have another OCC cluster, 2 or 3 RM clusters and a 9c1 cluster recently recovered.  Fig I should be able to figure out if it's a cluster issue, lol.  I'd rather not use the OCC cluster though as it has 115K on it and looks mint (unlike the rest of this car ha ha ha).

Fred, thanks for the info on the VSS signal. didn't know that as I cut my PCM teeth on the LT1 modules...

I'll be under the car tomorrow giving it a going over. It runs out great though and rides nice so mech it seems pretty good.
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91OCCWagon

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 5:08 pm

I have pretty much the same problem with my speedo/tach. I think i'll end up swapping out the cluster
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Fred Kiehl

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 8:36 pm

You do not have to swap out the whole cluster, just the circuit board on the back. That way you can keep the pretty OCC cluster. There are pins that hold the "motors" to the circuit board. Just a word to the wise; sometimes they are a little difficult to remove. Do not put so much pressure on them that it cracks the circuit board.
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91OCCWagon

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 9:13 pm

Oh ok, and I can get a circuit board from any 91-96 B-body?
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Fred Kiehl

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PostSubject: Re: Wonky Speedo   Wed Jul 03, 2013 9:41 pm

No, just 91-93 RM wagons, 92-93 RM sedans, and OCCs.
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Sprocket

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PostSubject: Re: Wonky Speedo   Thu Jul 04, 2013 1:29 pm

91 occ,

The TBI Caprices have a different shape cluster (it's smaller), unless you find a LTZ/9c1 which had a hybrid digital speedo/ analog tach and rest of gauges.

The 9c1, Roadmaster and OCC clusters are all interchangeable, but obvious the digital one is a little different on the on cluster circuit boards. I believe there are some minor bulb location differences (like no gate ajar on a sedan) but can be modded. As Fred mentioned I'd keep the OCC needles and face plate as they are better looking than the bricks. The 9c1 one is okay too, I just like the white needles on the Buick and the numbering looks less sophisticated IMHO

Pics avail in this thread

http://www.impalassforum.com/vBulletin/showthread.php?t=278627
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91OCCWagon

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PostSubject: Re: Wonky Speedo   Thu Jul 04, 2013 4:31 pm

Oh ok, thanks for that.

And sorry to hijack the thread but could this also be the reason my odometer/tripometer don't work?
I doubt it but i figured i would ask.
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