1990 speedometer not working
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 1990 speedometer not working
Would the passkey stop the vss signal from going through the ecm's buffer. he was able to blink a 46.
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Re: 1990 speedometer not working
YOU REMEMBER YESTERDAY I ASK THE QUESTION ABOUT VOLTAGE COMMING FROM THE SPEEDO? RBOB SAID 12V WAS SUPPOSED TO COME FROM THE SPEEDO TO B11.... THAT PUTS A NEW TWIST TO THINGS.....
Joined: Dec 2004
Posts: 16,694
Likes: 979
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 1990 speedometer not working
rbob was not on here yesterday ? The gm service manual stated to check b11
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Re: 1990 speedometer not working
thanks for the ecm offer, but I'm not going to stand back and throw money at this problem till I know for sure where to throw it.....My money is retirement check once a month and not much of that......
Joined: Dec 2004
Posts: 16,694
Likes: 979
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 1990 speedometer not working
b1 is in a weather pack connecter on the passenger side fender next to the battery.
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: 1990 speedometer not working
It should be the current vehicle voltage. ITS 1.73 VOLTS
But since you can get the speedometer to move by touching that wire (to ground?), NOT TO GROUND, WHILE I HAD THE WIRE CUT, THE SPEEDO WOULD MOVE BY TOUCHING MY VOLT METER PROBE TO THE WIRE... FASTER I TOUCHED, HIGHER IT WOULD GO....
I would work on the ECM end first. If the ECM is bad, can always wire in a 4-out buffer.... GOOD NEW THERE BUT DONT HAVE 4 OUT BUFFER.....
To check the ECM pulse stream output, use a resistor in the 4.7K to 6.2K range to that ECM pin (B11, B12, or C1), and the other end of the resistor to +12 volts (vehicle voltage). With no motion that will pull up the ECM output to vehicle voltage. With motion on the VSS most DVMs will show about half the vehicle voltage.....WHAT WILL THIS TEST PROVE?
RBob.
> most DVMs will show about half the vehicle voltage.....WHAT WILL THIS TEST PROVE?
It will prove whether the ECM is sending a pulse stream. I see two issues so far, the low voltage from the speedometer, and the no change in that voltage when the VSS is being spun.
Basically, by checking the ECM next we are moving up the VSS pulse stream hardware. You verified that the VSS is OK, next is to verify that the ECM is OK. If that works, it leaves the speedometer or a connector between it and the ECM.
As for wiring in a 4-out buffer, it is likely cheaper then replacing the ECM. Although more work is involved. If you do replace the ECM, be sure to swap the MEMCAL from it into the next one.
RBob.
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Re: 1990 speedometer not working
since the vss voltage goes to the ecm and the 1.73, which should be 0-12v, comes from the speedo. The speedo voltage can only come for the guage power source which is black and pink wire going to the small circuit board inside speedo housing. How would vss voltage change the guage source voltage? does anyone have the little circuit board in the speedo housing. That has to be the problem.... or one of the problems.
Last edited by K4KAK; Jun 6, 2012 at 04:21 PM.
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