Cruise control and wiper issue

[87Skier]

Just bought an 89 suburban and have been troubleshooting some issues.

The cruise control system doesn't work at all. I replaced all the vacuum hoses going to it, but have had no luck with it.

The windshield wipers only work in certain modes. If I try the mist setting it will stop as soon as the switch is released. The windshield wash works fine. None of the intermittent modes work. Slow speed and high speed work fine.

Do you guys think these issues are related or not? I'm thinking its the control arm, but I don't want to shell out $100 for a new one if that's not the issue.

Thanks

[68Timber]

Yeah, it sounds like the contacts in the stalk are worn.

[87Skier]

I ordered a new one and will update once I have it installed.

[Greenlee]

You might want to try replacing the wiper motor before tearing into the steering column. My wipers were acting like yours and I was convinced it was the switch. After replacing the intermittent wiper module and the switch twice, they still didn't work right. Finally, I replaced the motor and that fixed it.

[87Skier]

Update...

I replaced the switch, cruise still doesn't work and no improvement on the wipers.
I think I need a new control module for the wipers but I'm not sure about the cruise control.

Anyone have any ideas?

[Silverbullet555]

I may not be correct in my thoughts on how the cruise system works. I know it runs off vacuum. I'm assuming the servo has to be able to hold vacuum. Have you checked the servo to see if it can hold vacuum?

[87Skier]

I believe it holds a vacuum but I haven't directly tested it yet. I replaced all the rubber hoses last week since they felt like the original ones.

Anyone know how to check the electrical portion or know of a good description of the system?

[Ski-me]

Any check engine light? Does your speedo operate smoothly?

On the back of the speedo, there is an optical eye that picks up your speed (into a pulse), and then feeds a small, light green speedo type box. It translates that pulse and provides input to your cruise control and also your computer.

How is the linkage on the TBI and is it fully connected and adjusted? Any junkyards around where you could get another plunger?

Just a few thoughts for you....

[87Skier]

Check engine light has come on 3 times now but always turns off after a minute. It is always around 60 mph when it does come on.

I know the box you are referring to on the back of the cluster. Everything is connected. Not sure on testing each component here.

Above 50 mph the speedometer is very steady.

All the cruise control stuff seems to be connected properly. I don't think I will be able to find a new plunger assembly locally. I think I will have to get a new one to check that.

[68Timber]

Originally Posted by Ski-me

Any check engine light? Does your speedo operate smoothly?

On the back of the speedo, there is an optical eye that picks up your speed (into a pulse), and then feeds a small, light green speedo type box. It translates that pulse and provides input to your cruise control and also your computer.

How is the linkage on the TBI and is it fully connected and adjusted? Any junkyards around where you could get another plunger?

Just a few thoughts for you....

What is the optical eye taking a signal from? Did the CEL set a code?

[Ski-me]

Originally Posted by BRUISER

What is the optical eye taking a signal from? Did the CEL set a code?

It looks at the mechanical rotation of the speedometer and then converts that to a pulse (on the back side of the gauge). So if your speedo is jumping around from the cable, it also effects this optical reading and will ultimately provides an inaccurate reading to the computer and cruise control. If that pulse is too eratic, you would probably get some error codes.

I messed around with my cable with lube and then replacing the whole thing. Still jumped around a bit so eventually converted my 89' cable driven with the 90-91 electrical one. Now, the speedo is dead steady and my cruise control works great. I did replace my plunger with a junkyard one....don't remember if that was really the issue because I soon there after, converted to electrical speedo. Now my cruise is very solid.

[Ski-me]

Originally Posted by 87Skier

Check engine light has come on 3 times now but always turns off after a minute. It is always around 60 mph when it does come on.

I know the box you are referring to on the back of the cluster. Everything is connected. Not sure on testing each component here.

Above 50 mph the speedometer is very steady.

All the cruise control stuff seems to be connected properly. I don't think I will be able to find a new plunger assembly locally. I think I will have to get a new one to check that.

If your speedo is bouncing around at the lower speeds, try and get that fixed first. You can try a speedo lube (have to go in from back of speedo cluster) or just replace the cable all together. This would be a start.

I mentioned above I went to electric speedo to fix mine, but I also made the switch so I could get my speedo calibrated correctly. I installed a 7 pin toggle to the DRAC so I can basically dial in my specific axle ratio and tire size to get my speedo to read accurately. It is Spot on accurate with 33's or 35's and 4.10 gears.

[87Skier]

Originally Posted by BRUISER

What is the optical eye taking a signal from? Did the CEL set a code?

CEL showed code 13 (O2 sensor).

I'm not sure that the speedo bounce is preventing the cruise control from engaging. I feel that it would still work occasionally.

I think I'll go through the repair manual and see if I can find something on testing the electrical portion. Then maybe head out to the junkyard and see if I can get some of the parts.

[87Skier]

Another update...

Found that the brake light switch was faulty (not showing 12v at cruise module with the pedal up). Replaced it but still no luck.

Also, is there a light for the cruise control. I don't think my 96 has one, but I've been sure if its just burnt out.

[87Skier]

Finally fixed it. While checking the servo I kept getting infinite resistance on all the terminals. When I tried to remove the servo the connector just fell off. I reconnected it and everything works fine, kind of. I need to do the speedo upgrade.

Just a recap...
I replaced the lever and wire (wire was worn and showing in one spot).
Found that the brake pedal switch was faulty.
Reconnected wires at servo.


Any help on converting to a newer digital speedo?

[Ski-me]

Originally Posted by 87Skier

Finally fixed it. While checking the servo I kept getting infinite resistance on all the terminals. When I tried to remove the servo the connector just fell off. I reconnected it and everything works fine, kind of. I need to do the speedo upgrade.

Just a recap...
I replaced the lever and wire (wire was worn and showing in one spot).
Found that the brake pedal switch was faulty.
Reconnected wires at servo.


Any help on converting to a newer digital speedo?

http://coloradok5.com/forums/showthread.php?t=296187

Just happen to do a whole writeup on it! Let me know if you can't view it....
Posted via Mobile Device

[87Skier]

That's a well written write up you have there! It seems like it is pretty involved. I wasn't aware that I would have to swap out t-case parts. I might take a look at my spare 243 I have in my garage and see if they line up. My local parts yard is very irritating sometimes, they will make you buy the whole unit even though they have had it for 5 years and nobody wants the entire t case.

Another question for you, are your gauges really that bright? Mine seem very dim compared to yours.

[Ski-me]

Originally Posted by 87Skier

That's a well written write up you have there! It seems like it is pretty involved. I wasn't aware that I would have to swap out t-case parts. I might take a look at my spare 243 I have in my garage and see if they line up. My local parts yard is very irritating sometimes, they will make you buy the whole unit even though they have had it for 5 years and nobody wants the entire t case.

Another question for you, are your gauges really that bright? Mine seem very dim compared to yours.

It does help to spray the back side of the cluster with a "chrome" paint. It helps reflect the light bulbs better. It's not as bright as modern vehicles but it is vastly improved.

[87Skier]

Just an update in case anyone comes across this later on is wondering if I ever solved all the issues:

I ended up getting the tail shaft housing from a 90 Suburban with electronic speedometer and swapped all the parts on. I added in the DRAC module to communicate with the speedometer and I'm really glad I added the dip switch in the module (its a pain, but well worth it). It took some tinkering to get the speedo dialed in, but now the cruise control works perfect and the gauge is dead on.

[Ski-me]

Really is a great feeling after all that work, congratulations!! Bonus, you are probably sending a more accurate signal to your computer so engine may do a bit bett, too. Did you chrome the inside of cluster?
Posted via Mobile Device

[87Skier]

I did end up chroming the cluster. I still have a lot of work to do though. I have been looking over the clusters and some of the lights appear to be a slightly different size. My fiber optic cable (light for ashtray) doesn't want to fit. I may end up wiring in a low wattage light there.

I may also need to add a pin in the cluster harness for the 4wd light. It too doesn't want to go in. Oh well, it will keep me busy.

[68Timber]

Awesome, congrats on bringing it back around.

[Ski-me]

Originally Posted by 87Skier

I did end up chroming the cluster. I still have a lot of work to do though. I have been looking over the clusters and some of the lights appear to be a slightly different size. My fiber optic cable (light for ashtray) doesn't want to fit. I may end up wiring in a low wattage light there.

I may also need to add a pin in the cluster harness for the 4wd light. It too doesn't want to go in. Oh well, it will keep me busy.

You may check the switch on the transfer case. It's a simple little steel ball in there and mine went bad (unable to make contact I guess). I found another one at the junkyard and it was good to go. It's the only other wire connector on top of the transfer case. Might be able to test it by jumpering the connector with a piece of wire. That would tell you if the bulb in the dash is working correctly or not.

[87Skier]

Everything works ok except the bulb holder for the 4wd light. I see in your pictures yours is wired the same with the 4 wd light being on a couple wires coming from another harness. For some reason it wouldn't go in my new cluster.

I ended up making something and adding a pin in the cluster to power up the light.

Thanks for the suggestion though. My 4wd light can flicker at times. I suspect it is the part you are talking about.