'97 K1500 Suburban Cruise Control Issue

[df2x4]

So I think I have this figured out... Just wanted to get some input from others before I buy the part.

Long story short, I found out a couple days ago that the cruise control in my Suburban ('97 K1500) doesn't work properly when the windshield wipers are running. It will engage/set, but will shut off and start coasting after a seemingly random distance. Sometimes it'll stay on for a few hundred yards, sometimes a few miles. I took it on the interstate today (nice and sunny, no wipers) and the cruise worked perfectly.

Am I correct in thinking that this is an issue with the multi-function switch in the column that controls the wipers/turn signals/cruise? Doesn't seem to be related to the brake switch as the issue only appears when the wipers are running.

 

[someotherguy]

Hmmm....*maybe* ???

My hunch is that you've got a ground issue in one or the other.. or both, and using both motors at the same time makes the issue apparent.

I'd go over the circuit boards in the wiper motor and the cruise motor first, if you haven't. The wiper board re-solder job for the harness connector is well-known at this point, but the cruise motors not so much; a few people have had issues with them and solved it with going over them for any bad solder joints.

Richard

 

[df2x4]

My hunch is that you've got a ground issue in one or the other.. or both, and using both motors at the same time makes the issue apparent.

If they shared a ground, wouldn't this likely effect the operation of the wipers somewhat as well? They work fine on all speeds. Certified big dummy here, just throwing out thoughts.

I suppose it could be a ground issue, but post #2 in this thread (from Purefection) really makes me suspect the multi-function switch.

https://www.gmt400.com/threads/no-cruise-control-working-then-stopped.27559/

EDIT - I also noticed a few days ago that one of the turn signal indicators on the cluster wasn't working. Turn signals themselves worked fine, just the indicator for one of them wouldn't light up. I originally suspected a burnt out bulb, but that problem has since fixed itself. Not sure if these issues are related or not but figured it was worth mentioning.

 

[someotherguy]

The one reply from the guy with the '97 does imply the multifunction switch can be the cause. However the OP in that thread has a '94 which is an entirely different arrangement. The cruise switches and wiper switches on '94 and older are separate devices. There's no all-in-one multifunction switch like '95-up has. Everything separate.

If it was my truck I'd go after the wiper board and cruise board first, because it's easy and free, and they are known issues. The multifunction switch is a little pricey and a PITA to do.

(To clarify, '94-older the lever is referred to as a multifunction switch by GM, but electrically, all the parts are separate. Cruise switches are the only parts in that lever that are integral to it. It only physically activates a separate wiper switch, turn signal switch, high beam switch. It has tiny wires from the cruise switches that make a sharp bend before they go into the column and they are notorious for failing there, making it the #1 suspect in cruise failures on '94-older. '95-up shares nothing at all with this design.)

Richard

 

[1998_K1500_Sub]

Am I correct in thinking that this is an issue with the multi-function switch in the column that controls the wipers/turn signals/cruise? Doesn't seem to be related to the brake switch as the issue only appears when the wipers are running.

That's a reasonable suspicion. As a beginning, I would grab the wiring diagrams for 1997 and look to see which circuits (power, ground, others), if any, the cruise and wiper have in common in the MF switch or elsewhere.

 

[df2x4]

Good call. I do have a physical set of the '97 GM FSMs, I'll give them a look before I fire the parts cannon.

 

[1998_K1500_Sub]

EDIT - I also noticed a few days ago that one of the turn signal indicators on the cluster wasn't working. Turn signals themselves worked fine, just the indicator for one of them wouldn't light up. I originally suspected a burnt out bulb, but that problem has since fixed itself. Not sure if these issues are related or not but figured it was worth mentioning.

Power and ground for the turn signal indicators is shown here, in the middle of the 2nd page of the .pdf and on the 1st page.

Power for the indicator lamps comes via the turn/hazard switch, from a circuit shared with the corresponding external turn signal lamps on the front of the vehicle, as shown.

Power to the turn/hazard switch for all flashing purposes is supplied from the flasher at the connection denoted as "E9" (shown on pg. 1 of .pdf).

Evidently both indicator lamps are grounded at engine ground G103. The external turn signal lamps on the front of the vehicle are each grounded separately.

I might guess that you've got an indicator bulb with a broken filament, which quit working for a time (filament open) and then started working again (filament fragments touched and welded themselves back together, likely tenuously).

 

[Schurkey]

(To clarify, '94-older the lever is referred to as a multifunction switch by GM, but electrically, all the parts are separate. Cruise switches are the only parts in that lever that are integral to it. It only physically activates a separate wiper switch, turn signal switch, high beam switch. It has tiny wires from the cruise switches that make a sharp bend before they go into the column and they are notorious for failing there, making it the #1 suspect in cruise failures on '94-older. '95-up shares nothing at all with this design.)

Thanks for that. I've never dicked with a '95--up turn signal lever/cruise switch/wiper control.

Put several '94--older turn signal levers in place, though. All exactly as you described--wires frayed where they come out of the turn signal lever, so the cruise quits working.

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I never noticed that my '97 plow truck had a different cruise arrangement. Gonna have to go stare at the turnsignal lever for awhile tomorrow.

 

[someotherguy]

I never noticed that my '97 plow truck had a different cruise arrangement. Gonna have to go stare at the turnsignal lever for awhile tomorrow.

Yep. Something goes bad on '95-up and you're replacing the whole thing. The hazard switch is the one that takes the most abuse.

I tell people, if your '95-up hazard button isn't broken (sticking it in the "on" position), leave it alone and don't ever use it unless you're in an emergency situation in a dangerous spot on the road. If you pull the dash bezel for anything, be extra careful to avoid hitting the hazard button with it - these things are super easy to break, and all the functions are in one combo switch - signals, hazards, wipers, cruise, and high beams.

One "small wires" issue the '95-up design has that is a bit common is the high/low beam select wires are pretty small, and if you use the tilt column a lot, the wires can break. I'd say you could repair this pretty easily with some properly soldered and heat shrunk jumper wires.

Richard

 

[letitsnow]

Replacing the multi function switch on the 95+ isn't bad. You don't have to remove the steering wheel if you use a small 1/4" drive bit for the one screw that is on top of the switch.

I use my hazards often, and would not be afraid of them. It is a fairly simple set up.