Here's the deal. My speedometer, wait to start light, overdrive, and cruise control all quit working today.
I have checked the speed sensor & it's wiring. They are fine.
I found a burnt fusible link & replaced it.
I think the sensor power circuit may be burnt out.
Any suggestions guys??
Does anyone know how to at least get the speedo to work without the ECM?

 

when my computer when out i lost all of that plus the altenator wouldnt charge not at the same time but gradually one by one. I got a computer on Ebay with a lifetime waranty

 

oh, i forgot to mention. This is a 91.5 model, the one with no crank sensor & an external voltage regulator.

Everything quit working at once too.

 

I don't think you have an ecm...so that's good news!

One time my speedo quit working and it turned out to be a broken wire above my knee (above the parking brake pedal area).

I think 92 is when they went to the ECM gadgetry.

 

Actually, a 91.5 does have an ECM. It's right next to the battery under the edge of the fender. The early 91 models did not as far as i know. The 91.5 system is also a 1/2 year only system . . . .AAAAAARRRRRGGGGG!!!!

Unfortunately, after some looking through the wiring diagrams, testing voltages & experimenting i have determined that my ECM is indeed bad. All of the required voltages & grounds are there except the 5v output coming out of the ECM to the sensors. All of the wiring is good & when i supply the 5v signal externally the ECM comes alive.

 

Generally 'ECM' refers to the 'Engine Control Module'. This thing just runs on magic...and a rotary pump.

There might be a body computer of some sort that works the gauges, I don't really know for sure.

 

Actually, I just looked at the wiring diagram.
It's called an SBEC (Single Board Engine Controller).

it really don't do much though.

 

Why not just build a 5 V regulator power supply and supply the 5 V externally as you did for the test? Maybe you found the Achilles' heel of our computer systems.
Mike

 

I was thinking about that until i tried feeding power to the sensors. All that worked was the speedo & wait to start light. Nothing else worked.