my tach quit working

[critter2655]

Ok as you all know i have a 86 K20 well i got a instrument cluster, factory tach, and the tach wiring out of a donor truck, when i put it all in the tach did work, for a while at least. now all it does is reset from 1500 to zero when you turn the key on motor off. when you turn the key off it goes to like a 1000/1500 resting position. when the motor is running, the needle stays at zero. i have cheked the power and ground wires and they are ok, ive double checked the hookup on the distributor, the only thing that i know it could be is the round resistor thing in the coil/feed wire. can anyone tell me the exact name and where and if i can buy one, i even tried another factory tach i got as a spare and it just sent the needle around to straight down.

 

[89Suburban]

Diode.

 

[critter2655]

can you still buy those diodes for these trucks, and if so where at?

 

[89Suburban]

I posted just a guess, I have no idea. If you can get some pics up that would be a great help.

 

[crazy4offroad]

I think he means a diode in the tach. Radio Shack sells any kind you want but I would just as soon buy a new tach lol. Speaking of which I need a new one myself.

 

[RetroC10Sport]

http://cgi.ebay.com/ebaymotors/1973...rQ5fTruckQ5fPartsQ5fAccessories#ht_512wt_1008

 

[nvrenuf]

There is a small black "thing" inline in the ignition signal wire, that's the diode.

Your best bet is probably looking on Ebay for a harness only.

 

[critter2655]

well i found another diode, and well the tach did the same thing so im assuming its junk, is there any place that may still repair one of these?

 

[89Suburban]

well i found another diode, and well the tach did the same thing so im assuming its junk, is there any place that may still repair one of these?

http://www.tachman.com/oldsun.htm

 

[89Suburban]

http://www.instrumentsrus.com/gm.htm

 

[89Suburban]

http://clocksandgauges.com/gpage1.html

 

[89Suburban]

http://www.repairconnector.com/products/GM-HEI-Distributor-To-Tachometer-Connector.html