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#15031 - 09/03/02 03:46 PM Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
I've had an intermittent problem with my tach latetly. Let me give a little background and maybe you folks can give me some help. Around December of last year my tach would stop working at times. This happened while I was driving the car and when I would start it up. By the way, this was one week before I shipped my car to the Netherlands. Anyways back to the subject...I could shut down the car for the night, hope back in the car next day and it would work fine. So I took the car to the dealer who had it for a few days and 'said' they fixed the problem. So after driving around the Netherlands since January this problem has popped up a few times. It happens more frequently now. I've checked the D.I.C. for codes and get the following:

10 PCM P0654 H C

Looking at the service manual it says that this is the "Engine Speed Output Circuit." Could this be a simple problem as the PCM connectors are not seated properly?

I'm kind of at a loss here and since I'm in the Netherlands I don't have a Chevy dealer in my vicinity. C4C5 do you have any clues here?

Thanks for your help folks.
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15032 - 09/03/02 04:11 PM Re: Tachometer Problem!!
Buckmaster Offline
C5Forum Fanatic

Registered: 03/29/02
Posts: 355
Loc: Nothern Calif/ San Juan Island
Check tach wire connection. Pin #10 white wire on PCM, located in front passenger wheel well. sounds like a loose connection.
Good luck.
_________________________
2000 Vert loaded 6 speed.
478 RWHP

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#15033 - 09/03/02 04:33 PM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
Buck,
If I take the PCM and check this, is this something that could just be re-soldered?
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15034 - 09/03/02 07:51 PM Re: Tachometer Problem!!
c4c5specialist Offline
Member

Registered: 07/10/01
Posts: 1612
Loc: conn
Hi there,
I would concur with the Buckmaster here.
I do agree with this.
Also, if you have had the battery leakage syndrome, then maybe your wire has been eaten away.
This is also a possiblity.
Yes, you can use the 7mm to tighten the connectors, however, I feel that there is more to this than just a loose connector.
Like, maybe a worn through wire. Yes, you can repair the wire, or install a new terminal.
Please keep us posted, c4c5 hammer
_________________________
c4c5 Chevrolet dealership mechanic, ASE Master Technician w/L1. COFFEE ADDICT. A persons judgement is only as good as the information they have, which should be FACT, not fiction.


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#15035 - 09/04/02 03:10 PM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
C4C5,
Thanks for your input! I don't think that it is the battery leakage problem. I replaced my stock battery for an Optima before I left the states. hammer
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15036 - 09/05/02 03:35 AM Re: Tachometer Problem!!
Buckmaster Offline
C5Forum Fanatic

Registered: 03/29/02
Posts: 355
Loc: Nothern Calif/ San Juan Island
You may also have a bad Tac module, which is located near PCM.
My bet is with wire connection problem, since problem comes and goes.
Good luck.
_________________________
2000 Vert loaded 6 speed.
478 RWHP

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#15037 - 09/30/02 11:44 AM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
Folks,
I was finally able to take a look at the connector for the PCM. The number 10 pin(white wire) connector looks fine. The tach has quit working altogether now. Could I have a faulty instrument cluster? When I start the car up the tach needle moves to the rev limit and goes back to zero then just sits there. Any other ideas? I don't have any diagnostic equipment so I'm sort of screwed here. On top of that being in the Netherlands I really don't have a Chevy dealer that I could just stop by.

Thanks,
Murnutz
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15038 - 10/09/02 04:12 PM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
C4C5 are you out there? Any other thoughts?
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15039 - 10/09/02 05:29 PM Re: Tachometer Problem!!
c4c5specialist Offline
Member

Registered: 07/10/01
Posts: 1612
Loc: conn
Hm,
Very interesting.
Ok, try this, reset all codes in the PCM, and the DIC.
Then, start the car, reset all messages, and retrieve codes.
Post what you have, please.
I will recheck this evening.
c4c5 hammer
_________________________
c4c5 Chevrolet dealership mechanic, ASE Master Technician w/L1. COFFEE ADDICT. A persons judgement is only as good as the information they have, which should be FACT, not fiction.


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#15040 - 10/10/02 02:08 PM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
C4C5,
Okay I went and reset the codes and started the car as you said to do. Here is what I get now.

10 PCM P0654 H C This is the same as before
28 TCS NO CODES
40 BCM NO CODES
58 SDM NO CODES
60 IPC NO CODES
80 RADIO NO COMM
BO RFA NO CODES

As I stated earlier, I have looked at the PCM connector and nothing appears to be wrong with the wiring. The tach does the needle check to redline then goes to zero and just stays there. Any feedback that you can provide would be appreciated.

Thanks,
Murnutz
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15041 - 10/10/02 06:40 PM Re: Tachometer Problem!!
c4c5specialist Offline
Member

Registered: 07/10/01
Posts: 1612
Loc: conn
Hi there,
Unfortunately, this indicates that there is definately a problem inside the PCM.
You see, the PCM monitors the signal to the IPC for the tachometer signal.
Now, with that understood, if the PCM does NOT see voltage on this circuit, this code sets.
Now, without a signal generator to attempt to duplicate the signal, to make sure the IPC is working, I cannot be absolutely sure, however, if I was a betting man, I would say that if you replace your PCM, you will rectify the condition.
Its the only thing that makes sense, based on the fact that if you had an internal problem with the IPC, you would have codes there.
This is what I would suggest, as the PCM is about $150 US dollars, and the core is $250.
Please let us know if you can get one over there, ok?????
c4c5 hammer
_________________________
c4c5 Chevrolet dealership mechanic, ASE Master Technician w/L1. COFFEE ADDICT. A persons judgement is only as good as the information they have, which should be FACT, not fiction.


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#15042 - 10/11/02 11:36 AM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
c4c5,
If you say that you believe it is the PCM, then I would have to go with your hunch! Correct me if I'm wrong here, but doesn't replacement of the PCM requiring downloading of the old information such as mileage, etc...into some diagnostic equipment and then reloading that info back into the new PCM? Thanks for your help. You da man! hammer
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#15043 - 10/11/02 04:53 PM Re: Tachometer Problem!!
c4c5specialist Offline
Member

Registered: 07/10/01
Posts: 1612
Loc: conn
Hi there,
You must download the engine calibrations, and other information to the specific vehicle identification number, at the lower corner of the windshield.
If I have your VIN, I can program a PCM here, and send it to you if you need it.
Just let me know what you need, c4c5 hammer
_________________________
c4c5 Chevrolet dealership mechanic, ASE Master Technician w/L1. COFFEE ADDICT. A persons judgement is only as good as the information they have, which should be FACT, not fiction.


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#15044 - 10/12/02 11:54 AM Re: Tachometer Problem!!
murnutz Offline
European Travel Guide

Registered: 12/29/00
Posts: 185
Loc: Springboro, Ohio
c4c5,
Can you send me an e-mail so that we can discuss this offline? I am going to Spain for about five weeks and would like to get this fixed when I return.

murnutts69@hotmail.com

Thanks,
Murnutz
_________________________
'99 Pewter FRC - mods include Breathless vortex rammer, B&B PRT exhaust w/speedway tips, Hurst shifter w/MGW gripper shift knob, Y2K chromes w/Yokohama AVS sport tires(255/40R17 in front & 285/35R18 in rear), cross drilled/slotted rotors, and ZO6 calipers

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#113960 - 02/25/21 09:50 PM Re: Tachometer Problem!! [Re: murnutz]
Poobahh Offline
Just Started the Engine

Registered: 02/25/21
Posts: 1
What did you ever do to fix this?

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