I have a weird problem with the cruise control on my '89 Delta. It only works sometimes, totally at random. I have not found any kind of reason or logic for why it works when it does.

For instance, last night after I got on the highway I found that it wasn't working. This pissed me off because I had a long way to go. After about 10 minutes or so I accidentally slid the cruise control button to the right, into the accelerate/resume position, and the cruise kicked in and brought me back up to 70 mph. Tonight on my way home from work I tried the same thing. It didn't work at first, but it still didn't work after driving a while.

Bad connection maybe? Check the wiring.

I am not sure about the '89 models, but on my son's 93 Buick LeSabre he had some trouble with cruise. His car has OBDII and it turned out to be a black box located under (behind) the dash near the glove box. I wish I could remember the name of it. Anyway, the way he found it was to read the codes the vehicle displayed when shorting two pins on a connnector together, then he read in the shop manual what that code meant and what it affected. One thing it affected was the cruise control function, so we changed it and his cruise works now. I am sorry this is a vague post but I just can't remember the specifics and it would probably be different for your car. What I recommend you do though is get a shop manual, check your engine for codes and go from there.

OldsGuy, while trying to figure out why my head unit isn't working (I had the dash apart) I saw two black boxes - one had a blue & white label which read "Engine Control Computer" and it had several plugs coming out of the bottom. The other was a rectangular shaped fuse panel with 5 fuses in it. Either of those sound familiar? I hope it's not something with the ECC. I had a computer go crazy on me in my '84 Firebird S/E. Not fun stuff.

the 93 was more likely OBDI as this style will let you short the diag term to ground to retrieve SES "flash" coding.
schippa, gravereapper is prob on to the problem as i have encountered numerous times where the cruise wiring from the turn signal stalk are pinched inside the steering column, sometime caused by enthusiastic (slamming) of the turn signal lever (it is a switch, not a **tch, lol) or problems with the tilt system shorting the wires etc.
to test for this, while sriving and trying to activate the cruise wiggle the turn stalk around and if she accelerates/decels you have found your problem. also it is possible that there is a vacum leak and it isnt getting enough manifold vacume to actuate the trottle (this can happen if the engine never goes to closed throttle (creating high manifold vac) on extended climbs) i havent really seen many cruis control units (the actual servo assmbly) fail but it does happen.
if none of this works, follow oldsguy's advice, and get a shop manual for your car and look at a possible code that wont trigger the dash light.
the ECC is a fairly sensitive component but on you vehicle doesnt interface with the cruisecontrol system (the CC uses the VSS signal and brake switch as it's primary modus opperandi and activated the throttle machanicly while the ECC does it's thing as if you were just pressing the pedal down etc. do not jarr or shock the ECC (there's a reason it's in a good solid bracket) and the fuse block probly is an aux for elec climate control and maybe BCM (body control module) functions such as courtesy lights (some dim them slowly) twilight sentinel etc.

Thanks for the correction turbo, I had a feeling it was OBDI but wasn't sure. What is really ironic is that I am an electronics technician with 27 years of experience, to bad it was all in radar and communications though. I think you might be onto something with the tilt steering stalk causing wiring troubles, I have seen those problems a lot with all of the stalk mounted functions (wipers, turn signal, cruise, etc).

I helped my son with his car because the manual warned about ESD damae to the device we changed, probably the ecc, so I did it for him.

I have a 94 with an OBD II connector on an OBD I system so no papercliptrick for me.


60 dollar to read the codes.

So I am left with no cruise.

my switch tested good, all fuses tested good. go figure....

I am willing to bet Hans that your vehicle is a late 94 model year production (7/94 or 8/94) that makes it an intermediate model-essentially that as the OE's were req to produce OBDII vehicles most are half breeds ("mutts") if you forgive the analogy, of the OBDI computers with OBDII system components. from experience these are some of the hardeer cars to diagnos some issues, as most do not have true bidirrectional comunication with a scantool. they are not bad cars at all they are just development vehicles (if ya look at the obdII conector i am willing to bet that there are 5 or less terminals actually used where an OBDII (96 later) often have 6 or more, dep on BCM/cluster computers etc.) I have to believe though since you do not have a SES light on that your problem is prob mechanical/vacum based.
look on your drivers side fender (i think thats where the cruise controller is on your 3800) look for a unit with a cable going to the throttle body linkage if the unit has a hose and a diaphram it is the older vacum servo type, if the unit hase a flat connector with 6 or more wires and no vacum hose conected to it then it is a stepper motor/servo type and it may have stripped teeth causing intermitent problems but you will need to go into further diagnostics to be sure. shop around there may be a shop that is cheaper, you never know.
schlim

yeah I think the cruise control is controlled by the PCM. All I know is that it is really pissing me off.

How can I get color codes to check the resistances on the swich?

yes it is missing most of the contacts on the connector.