84 digital dash question

[knightranger]

i have a 84 n/a with a digital dash everything works but the speedometer read 0 constantly. I have done the test according to the fsm to check the speed sensor and i have also made sure the cable works, they both test good. I got another digital dash (at a junkyard) and it is doing the same thing any ideas?

also i have an 87 digital dash power supply and harness that when plugged into my 84 the speedometer and everything will work, but when it is plugged in things like headlights turn signals etc. wont work. So if there is a way to merge the two harnesses and make it work i can do that

[knightranger]

Correction I have the 87 digital dash, and power supply hooked up

[evildky]

your 84 had the speed sensor under the hood, the 87 had it in the trans, the engine/trans harness is different, I suspect you can still make it work just a matter of getting the right wires to the right wires.

[AZ-ZBum]

your 84 had the speed sensor under the hood, the 87 had it in the trans, the engine/trans harness is different, I suspect you can still make it work just a matter of getting the right wires to the right wires.

False. All digital dash cars have the sensor on the right strut tower just in front of the battery.

Only the 87-89 analog cars had the speed sensor on the transmission.

i have a 84 n/a with a digital dash everything works but the speedometer read 0 constantly. I have done the test according to the fsm to check the speed sensor and i have also made sure the cable works, they both test good. I got another digital dash (at a junkyard) and it is doing the same thing any ideas?

also i have an 87 digital dash power supply and harness that when plugged into my 84 the speedometer and everything will work, but when it is plugged in things like headlights turn signals etc. wont work. So if there is a way to merge the two harnesses and make it work i can do that

If I had to guess, it's because there is a huge difference between the 84 and 87 digital clusters. There are probably a lot of wiring differences in the dash harness itself that prevents them from mixing well. You're either going to have to find a functioning 84 cluster or read the 84 and 87 factory service manual wiring diagrams and verify every wire at the connectors.

[knightranger]

Thanks for you guys help I found some broken wires after removing the factory harness works great now