90 Caprice tach wire ?

Hello Everyone,

I have a problem locating a tach wire on a 90 Caprice.  I'm installing the autopage RS-855LCD.  In my chart (which you can't always go by) says the wire is suppose to be PURPLE / white or white @ the coil. Now at the coil, the wires are reading more ,way more than 1 to 6 volts.  I did find a green wire mounted to a module on the firewall it had 3 wire coming out it, (green, white, & pink) that gave me the 1 to 6 volts from the green , even when I accelerated the meter started to rise & when let off of the accelerator it dropped back down.  I figured this was the wire but when I turned the ignition off the meter was still reading voltage & it started rising, pegging the meter.  The 855 is not accepting this as a tach reading to program the remote start.  This car is fuel injected but it doesn't have the fuel rails to tap into. This set up has a carberated style housing with 4 little modules on top each of them having 2 wires coming out of them but they didn't give me the correct reading either.  Could anyone help me out.  Thank you in advance. 

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electronics

I find the best way to find a tach wire is at the ECU and I think your Caprice is the same as our Holden Statesman so should be in left hand kick.  Worst case get it behind the cluster and try a LED test light using the negative pole as probe while the positive is on constant.  That way you wont blow anything.

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WOW Sight and Sound
Maroochydore
Nothing is impossible!
Do it right the first time or don't do it at all.

Your car is throttle-body injected, hence no injector rails.

The white wire at the coil is the correct wire, do you have your meter set to read AC voltage?

Yes, I have the meter set on the ac side at the 10 scale because the voltage is suppose to read between 1-6 volts & the white wire that's coming out of the coil is pegging the meter on the 10 scale on the ac selection??

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electronics

What does it read if you up your scale? Have you tried to use that wire? Does there happen to be a purple white at the ignition coil?

To be honest, I am lazy...with most GM in that age bracket, I do not even bother metering the wire. I just hook to the white and program the tach, so it may indeed provide more than 10volts. It is more important to have a noticable difference in voltage as rpm increases and decreases than the actual voltage of the wire.

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Installer, IT support, and FFL. I need less hobbies.

MCEP, I have not tried to use that wire.  Reason being that it registered more than 6 volts actually pegging the meter.  This guy is going to bring it back this Saturday & will try that white wire.  I did not see a PURPLE / white.  Thank you guys, everyone for the help.

I have another question nothing to do with the previous subject.  I have a jeep & the blower motor for the heat,ac, & defrost only worked on high.  It use to work on the low & med levels, now it's not even working on high.  This just happen today.  My question is ( I did check the fuse, it was good) could that be the switch going out or went out.  Seeing how it only worked on the high position or the motor itself?

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electronics

Not sure if it is the same problem, but had a newer dodge caravan with a similar problem. Had to change out a controller pack that was mounted in the ductwork.

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Installer, IT support, and FFL. I need less hobbies.

Ok , thanks for that info!

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electronics

Caprice: The ECM should be somewhere under the passenger's dash----probably in the kick panel, possibly behind the glove box. You could always hunt up the tach wire over there.

(It is a sedan, right? The station wagon remained carbureted until the new body style came out for 1991.)

Jeep: Like twelvoltz says, probably the resistor pack---they do fail from time to time, and they're not expensive.

Find the climate-control blower motor under the hood; should have two thick wires. Follow those to the resistor pack. You'll notice that it's mounted so it's exposed to the climate-control's airflow, for cooling.

Thanks Twelvoltz, one thing I neglected to add was the motor made a squealing noise before it stopped working.  That's why I'm leaning towards the blower motor & the resistor pack, seeing how it only worked on the high position.  I can't get to the blower from under the hood because it's enclosed.  I probably have to go inside on the passenger under the dash.

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electronics