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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 12803
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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1985 Trans Am Tachometer not working. Yes, haven't tried

Customer Question

1985 Trans Am Tachometer not working.
JA: Are you fixing your Trans Am yourself? What have you tried so far?
Customer: Yes, haven't tried anything yet.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 11 months ago.
Category: Chevy
Expert:  Randall C replied 11 months ago.

Hello, I assume a 5.0 litre as you said trans am? if so, do you have multipoint injection or tuned port injection? lastly, does the check engine light come on with key on only?

Customer: replied 11 months ago.
it is 5.0. Has a carburator. Check engine light does not come except when first starting car.
Expert:  Randall C replied 11 months ago.

that is what I am asking the light does work with key on only? NOt running?

Expert:  Randall C replied 11 months ago.

ok, can you go to the distributor and tell me the wire colors going into the distributor? There were a couple different options

Customer: replied 11 months ago.
The ck engine light shows when engine is started with the other idiot lights, then extinguishes when motor is running. Tach runs to high as car is driving.
Expert:  Randall C replied 11 months ago.

ok, this is different information. You said tach not working. Is the tach reading higher than engine is running? meaning how high is tach running driving at 55

Customer: replied 11 months ago.
That is it. At 55mph tach reads 6000RPM's.
Expert:  Randall C replied 11 months ago.

ok, thanks, ***** ***** only one wire running from the ignition coil to the dash, That wire is off the NEG side of the coil. If there was a problem with coil? car would not run or run real bad, You are obviously getting a signal to the dash thus tach does work but readings are off, the tach is "solid state" meaning a real mini logic module inside the tach, The high reading is due to a bad tachometer. NOT a fuse or wire from tach to coil.

Customer: replied 11 months ago.
Then , I will need to replace tach?
Expert:  Randall C replied 11 months ago.

yes, you remove the trim, the the cluster, then the tach. here are some basic pictures