Mystery in a red box

[tucsonjwt]

So today I finally opened the 4" square red box marked AC Delco that is hanging from a harness above near my accelerator pedal. It keeps falling down and I have not yet found a good place to secure it.
What's this? - a printed circuit board with various electronic "bugs" on it.
I thought my 83 C20 was computer free.
Does anybody know what this PCB is for?

[gchemist]

Cruise control module.

[grinch4om]

anyone have a wiring schematic for cruise on an 84?

[tucsonjwt]

Since I may need to replace this module, I am looking at parts online, but the only one available is Standard Motor Products p/n CM4037, which looks nothing like mine (appears to use male, not female connector, like I have.)
Is there a reliable source for this module? I have a part number on the circuit board (25031662D) but I can't find that p/n online anywhere. Pics below.

[gchemist]

Only factory manuals have diagrams. I'll check my 83 manual. It has a whole section on cruise control. As for the box, I gave up finding one. I ended up with an aftermarket cruise control system.

[tucsonjwt]

Thanks gchemist. AC Delco and the dealer catalogs don't list a module for my 83 at all, and the aftermarkets look wrong. I browsed all of the cc modules I could find in this general model year range, and none had the 3 tab circuit board feature in the connector slot. I think 83 was the first year for this module type, vs. transducer type, cc.

[gchemist]

If I remember correctly, my 83 manual might have both versions. I know it has wiring diagrams. I'll get it scanned tomorrow.

[tucsonjwt]

Thanks. My response from GMpartsdirect today was: "The part number you requested has been discontinued and is no longer available from GM." I hope somebody has one NOS or aftermarket somewhere. Just having the GM or Delco part number would help.

[SBTork]

If that's the cruise control module, I may have found the newest GM number for it. I assume your '83 C20 does NOT have a 700r4 transmission. If that happens to be the case the number is 25074015, but they're also discontinued and I only see one dealer in the nation that says they have one in stock, no price either.

[tucsonjwt]

Thanks. I put p/n 25074015 in the Standard Motor Parts cross reference and it shows a different style of module - same style for all 1983s and up - which does not match my 3 tab PCB. I can't find any type of 3 tab PCB module - all of the similar styles are 2 tab. I guess I need an official GM photo of a p/n which matches my 3 tab PCB.
I got an email back from Standard Motor Products, saying that they can rebuild the module as a last resort, so I emailed them back and asked how they could rebuild the PCB if they did not have the manufacturer's specifications for it.

[79gmcc15]

Cut the wires and see what stops working!

[gchemist]

Try this site: http://www.obschevy.com/

[tucsonjwt]

obschevy.com states that they only carry parts through the 1970s. I think I am still in the same spot without a GM part number for a 3 tab circuit board module.

[tucsonjwt]

I am beginning to think that my truck did not come standard with CC and it was added sometime after purchase. Still, in looking at the dozens of modules for later model vehicles, I see no 3 tab circuit boards.

[gchemist]

Cruise control wiring available. Unfortunately too large to attach. Send me a PM with your address.

Hey Chris, I have a file to add to your wiring diagrams.

[Consaka]

I know this is old but it was the only site that came up when i asked google about the part number.
If it really is a cruise control module and it had gone bad they could easy fix it by testing the various components against the component flowcharts. Assuming the chips are all off the shelf stuff and none made special for GM.
Mine was in my 1983 diesel chevy van. My van is so custom I can no longer use the original speedo and the sensor for the cruise control is on that. Removing it could save some space I guess.