Speedometer swap

[wheels87k5]

What do you do with the plug/wires at the back of the stock speedometer?

The new speedometer is an Autometer and doesn't have a place for that plug. The speedometer cable also had to be changed because the new speedometer has threads on gauge end. I was able to use a cable for an older blazer. Same length and everything.

Without that plug attached to the stock speedometer you get a code 24 which says "circuit fault in vehicle speed sensor". And the trans will not shift to OD.

Is there an override or is there another aftermarket speedometer that uses that plug/wire set-up?

 

[JDNobodi]

Here is an adapter for the GM cable to aftermarket speedos.http://www.jegs.com/i/Equus/390/9873/10002/-1?parentProductId=1760320

I'm typing a responds the engine code.

 

[wheels87k5]

Thanks for the help on the adapter.

What I need now is help with the wiring that plugs into the back of the speedo and is held in with a small screw.

The new speedometer doesn't have a spot for that wiring setup which I believe is the VSS signal?

 

[JDNobodi]

I not really familiar with the 87 torque converter lock-up. So if I had to guess as how it works from your description, the factory speedometer has a speed sensor and when you changed speedometers you lost your speed sensor.
I once did a job where a person did a LTI swap and ECU needed a signal from a speed sensor. He didn't want to add a sensor to his transfer-case so he used one of those new GPS speed sensors for Dakota digital.
http://www.summitracing.com/parts/dak-gps-50-1/overview/
That is a little pricey though.

 

[wheels87k5]

After more searching, looks like there are 2 options.

1. Go with electric speedo and use adapter at transfer case to keep cable.

2. Go with electric speedo and DRAC setup.

Interesting.

 

[Deuling]

You forgot go with GPS speedo

 

[sweetk30]

the little wire and box unit is the optical speed sensor for cruise and tranny function.

as to bypass not sure . try eagle mark here he is the mod in the injection section and knows the electronics end real good.

 

[wheels87k5]

You forgot go with GPS speedo

That would be nice to have......do I leave the old speedo hooked up so the ECM gets the readings and just install the GPS unit?

Or do I remove the old stuff, and what to do with the code 24?

 

[dyeager535]

You want/need VSS to get TCC to lockup. Thre are workarounds to that of course, but you'd have to have someone get specific with you on the 700R4 and how to wire it up properly. The '82-86 trucks used vacuum for lockup instead of the ECM, so the parts are out there.

Electric speedo and DRAC are my preferred options, but that means keeping the stock speedometer I assume? Getting rid of the speedometer cable is nice, as are gear ratio/tire change corrections.

 

[82355]

After more searching, looks like there are 2 options.

1. Go with electric speedo and use adapter at transfer case to keep cable.

2. Go with electric speedo and DRAC setup.

Interesting.

3. Leave stock gauges in place.

Martin

 

[wheels87k5]

3. Leave stock gauges in place.

Martin

Too late......everything has been replaced with autometer. And all, except VSS for speedometer, is working.

 

[wheels87k5]

You want/need VSS to get TCC to lockup. Thre are workarounds to that of course, but you'd have to have someone get specific with you on the 700R4 and how to wire it up properly. The '82-86 trucks used vacuum for lockup instead of the ECM, so the parts are out there.

Electric speedo and DRAC are my preferred options, but that means keeping the stock speedometer I assume? Getting rid of the speedometer cable is nice, as are gear ratio/tire change corrections.

Yep....agree. I found your thread on VSS and thought it was a good one.

http://coloradok5.com/forums/showthread.php?t=216930&highlight=vss+needed

Looks like I'm headed toward using the adaptor from http://www.jagsthatrun.com/

Hope to go all electric/no cable in the future. Found the write up on setting up the 89' np241 to make it electric/DRAC. Maybe my next vaction project.

Thanks for the help.

 

[dyeager535]

Which adapter? Be careful with JTR...they are pretty good, but not quite "up" on the truck stuff, and not always correct.

Cruise may not work. I'm sure at some point I knew what PPM cruise needed, and for some reason I'm thinking it's not 2K PPM which is what the ECM needs. I personally got sick of not having cruise.