Greetings fellow Chevrolet Suburban owners!!!! Well, almost done with my 1987 Suburban 4X4 restoration, now, the cruise control does not work. After prodding, poking and test driving, it seems the cruise control servo is not working. Well, I can NOT find an original GM unit, PT# 25074630 OR a Cardone reman unit, PT# 38-1630. I was wondering if ANYONE out there had a cruise control servo you could sell me OR guide me in the right direction to locate one. I have tried O'Reilly's, NAPA, Advance Auto, CARID, Summit, Rock Auto-don't want to send in a "We MIGHT can fix it and if NOT, we send it back to you" sort of deal. I just want to purchase another working unit. I did find a video of how to disassemble the unit and replace the little foam filter inside. I did that and the factory book has three servo OHM readings to check and they all three check out fine. The module checks out (Using a Fluke DVOM) with the switch when the plug is hooked up. The fuses are good, the vacuum harness is good and working, the brake light switch is all working so I'm am taking a break. The turn signal lever is all new and I checked it again, it's good to go too. I really want to know....when you remove the two solenoids (VERY CAREFULLY) and remove the small spring AND rubber ball on top, there is a small pin on the OTHER side of the servo that is connected to a hidden diaphragm, and it DOES NOT come out. It doesn't separate to gain access to that diaphragm UNLESS you have to remove the light colored plug with the very small hole in it on the opposite side....I THINK. Has anyone ever ventured this far into it? Just looking for a really good answer. Thanks to all for your time and keep those Burb's running!!!
CK5
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1987 Chevy V10 Suburban 350 V8 4X4 Cruise Control Servo??
- Thread starter Heckler
- Start date
I have never dug into a non-working system, let alone into the servo. There are used ones out there, but getting one that positively works, and isn't just about to die, is the same as getting a new part, except for the warranty. I have pulled several of them solely based on the fact that the tab for the link is not worn through. No idea about testing it for proper function.
I do wonder about putting a newer cable operated servo on from one of the late nineties trucks.
I do wonder about putting a newer cable operated servo on from one of the late nineties trucks.
Apparently the cable ones such as used on S10s with electric servo will work with no other mods. Uses the same input as the stock setup for our trucks. I personally havent dug into it, but I should. Eliminating the reliance on vacuum and associated components would be nice.
Anyway...never dug into one of these things. My setup has decided to act up after sitting for 8 months, so I'll probably end up digging into mine too. Previously I did have a problem with the ebrake switch. For some reason it was super touchy, but also not clipped in firmly, so I adjusted the switch so it wasnt just barely engaging, then used a hose clamp over the cheesy spring fingers GM felt was good enough, to make sure it didnt slip in the future. Just make sure the ebrake switch is adjusted properly, from my experience that does seem to be a likely source of problems. Especially if the rest of the electrical checks out.
Anyway...never dug into one of these things. My setup has decided to act up after sitting for 8 months, so I'll probably end up digging into mine too. Previously I did have a problem with the ebrake switch. For some reason it was super touchy, but also not clipped in firmly, so I adjusted the switch so it wasnt just barely engaging, then used a hose clamp over the cheesy spring fingers GM felt was good enough, to make sure it didnt slip in the future. Just make sure the ebrake switch is adjusted properly, from my experience that does seem to be a likely source of problems. Especially if the rest of the electrical checks out.
black dawg
1/2 ton status
any idea what years??
Unfortunately I cant recall. I want to say it was early and/or mid 90's. All I remember is that it's a black box with the cable coming out of it, vs. The vacuum diaphragm of earlier. I bet you could go nearby year in rockautos catalog to see when it changed over from the style our trucks used, and how long that style ran.
It seems to me there are 3 switches on the brake pedal. One is NC, I think for the torque converter lockup. The other is NO, for the brake lights. I can't remember which one the cruise uses, but that should be clear from the wiring diagrams. There's also that vacuum switch for the cruise. Has all that been checked for function and adjustment?
Good morning fellow square body owners! I disassembled my old servo and carefully cleaned and resealed any areas that looked like problem areas. I am getting ready to re-install it and do a test drive. I wonder if there ever was an "Old style" cruise control tester used in the dealerships. If I can really figure out a way to rebuild them myself, I'm sure many square body owners would be very happy. I would even consider re-wrapping the insulated magnet wire on the solenoids too. Oh well, I will give it another go when the weather gets better here in North West Florida. MANY thanks for all the great answers/advice, I really appreciate it.
Did you take any photos of the innards? Always interested to see that stuff. I don't believe the manuals ever showed how to work on these, so they must have just replaced when broken.
Greetings Dyeager535 and thanks for the response. No, I didn't take any pictures because I found a YouTube video of a guy taking one apart and testing the innards, it showed the little foam filter inside that usually rots and causes problems. It's not hard, just BE SURE to know how the inside rubber o rings go against the metal plate with the two solenoids. I replaced those with regular black o rings. I actually broke one wire and managed to solder it back to the broken tab. MAKE sure you do the usual component disassembly task, just like a carburetor, HAVE A CLEAN area to work in and DON'T let anything roll off the table. Don't ask how I know this.....AND the factory wiring book showed the connections that are labeled in order to use an ohm meter to check the solenoids. And last, the big o ring that goes in the main diaphragm itself, I did NOT have a replacement so.........................I used RTV sealant ON THE OLD O RING and made sure it didn't leak. I checked the big o ring by putting pressure on the vacuum line taps and originally, it was leaking.....but...not anymore.
