Help!! Factory tach conversion
 

I have an 87' short box 4x4 with a three speed manual , it came factory with the 5" speedo and 5" fuel gauge with warning lights, picked up a gm NEW factory tach, with gauges , I was under the assumption it was the same pigtail plugging into the back of the cluster and might have to change some senders and hook up the tach wire obviously, well I've done that and I have NOTHING, speedo (mechanical) works obviously but all the gauges are pegged except the fuel gauge reads 1/4 but it's full, also the rh blinker indicator light is in as soon as the key is on and stays that way, also no blinkers working inside or outside, is there a diff pigtail for the factory tachs that anyone knows about? All help is appreciated thanks
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Re: Help!! Factory tach conversion
 

My 67 just had idiot lights. I know when I put the tach cluster in it I had to change the whole fuse box and wiring harness.
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Re: Help!! Factory tach conversion
 

Yes, trucks with factory gauge clusters (with or without the tach) have the wires in the cluster plug arranged in a different pinout configuration than trucks with the warning light clusters.

See the factory wiring diagrams that hatzie posted at --> http://67-72chevytrucks.com/vboard/s...d.php?t=545416

You can "re-pin" the cluster plug to match the factory gauge cluster configuration and that should take care of your problems. Do that by labeling all of the wires (using the warning light cluster diagram). Then carefully remove the terminals from the plastic connector housing (do that by depressing the latching tang using a tiny screwdriver or pick). Then re-insert them into the appropriate slots (this time using the diagram for trucks with factory gauges).

EDIT: What I just posted above is assuming your new gauge/tach cluster is meant for a 1978-1987 pickup truck. The 73-75 & 77-76 clusters (and clusters for medium duty trucks) each have thier own differences that would require additional wiring changes.

Re: Help!! Factory tach conversion
 

Thanks for the help, that makes sense and yes is for the 80's pickup
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Re: Help!! Factory tach conversion
 

should look kinda like this

Re: Help!! Factory tach conversion
 

Instrument cluster plug pinouts from the 73-87 FAQ.
http://67-72chevytrucks.com/vboard/s...d.php?t=456877