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'86 951 - almost stock
Join Date: Feb 2015
Location: Treasure Coast, FL
Posts: 7
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bare minimum to have cluster work
1986 - 951
Just finished cooling system, interior is totally gutted, car starts & runs great in garage, I want to see what the cluster gauges read - mine is only showing red light on volt gauge - nothing else working !!! No tach, oil pressure, fuel....... nothing Besides the "A-B & C" plugs on back & fuse # 18, what else should I be looking for ?!?! Thanks in advance |
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04-20-2015, 06:36 PM
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Registered User
Join Date: Nov 2010
Posts: 108
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Assuming the voltmeter itself isn't reading anything I would first check the voltage at the fuse (18). The voltmeter is driven directly by this. If the voltage on the load side of the fuse measures as good then next I would check the ground at MPIII. Next I'd check, if you can get to it, the voltage at the connection to the cluster itself: Plug C, pin 5 should be +12V and Pin 8 should be ground. (There are a bunch of other +12 and ground pins on the cluster but these are the two that supply the voltage indicator.)
If all these are good then there may be a problem in the connections/harness from the fuse and/or ground to (or in) the instrument cluster. Check the cables with an ohm meter and carefully inspect the cluster itself for anything suspicious looking... but since nothing is working I'd first suspect, and look for, a problem at the fuse or ground. Last edited by notMyScreenName; 04-22-2015 at 01:31 PM.. Reason: clarity |
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04-21-2015, 08:34 PM
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'86 951 - almost stock
Join Date: Feb 2015
Location: Treasure Coast, FL
Posts: 7
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Turns out - There is a red plug in passanger footwell that mates to a red plug which feeds a-b-c plugs in back of cluster
all works as should except the temp gauge, which at key pos 2&3(run) temp gauge is automatically at the top temp switch & sending units at head appear new, I have re-done the wires on both about 3" back, with protected fem connectors, and a generic square snap clip thing back to the elec wiring diagrams !!! Any help is greatly appreciated |
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04-23-2015, 07:29 AM
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Registered User
Join Date: Nov 2010
Posts: 108
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The temperature sensor for the temperature gauge is an NTC thermistor - meaning that as the temperature goes up, its resistance goes down. If the gauge goes all the way up as soon as the power is applied (assuming that the meter itself is good) then it is likely that either the sensor is bad (it's easy to test, Clarks has a procedure) or the cable from the sensor to the cluster is shorted to ground. The sensor connects to the cluster at A-12.
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04-23-2015, 06:36 PM
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