cruise control 2000 gmc 6.5

[zero76c]

hello can anyone tell me where to start to look for cruise control not working have power to all fuses can not find control module for cruise is not the same as 98 models

[Robyn]

Hello
Welcome to TDP

The cruise is controlled off the ECM I think.

Did it just stop ???

Might be as simple as a faulty switch on the brake pedal.

Best way to wrangle this out is to scare up a copy of the wiring schematic and trace out the circuit for the cruise.


I have not dealt with any 6.5 rigs newer than 95 myself, but others may chime in and offer assistance.

Robyn

[zero76c]

thank you for your info i have tried the brake switch check the bulbs i am trying to find the control module and the cruise never work from day one of buying the truck i have had it three years but really just started to drive it more often now and would like the cruise to work when i am on the highway i am not much of a computer person and everyone tells me how you can go on the internet and find anything not true for me i have search and search for info on 2000 diesel but all i found was a video on a 98 gas job and i do not have a controller on the fire wall as the 98 does and have found no other info so i thought i would try this forum but as you can see you're the only one who has replied i am not sure where to find a wire diagram either i get all kinds of advise but when i try to look it up i can never find anything lmk your thoughts
thank you

[trbankii]

The computer makes it a bit more tricky. You can’t just trace out the wiring diagram like you could with a non-computer system. That it has never worked for you adds a level of difficulty to the issue - as opposed to “this happened the other week and it stopped working.”

Best you can do is to verify that the components are working - brake switch, column stalk, etc. If you find something that isn’t working, replace it. If everything seems to be working, then it is likely “inside the computer.”

May be easier to just take it to the dealer to see if they can scan for the issue.

[Robyn]

Do you have, or have access to a top notch scan tool ??

If not, as mentioned the dealer can scan with their tech tool and likely find out whats up.

A tech tool will allow you to see if the system is getting a signal or not.

Good luck

[john8662]

Robyn is on top of it with the scan tool.

You must have this scanned for codes. Many codes that are engine related to the fuel system will disable the cruise control portion of the computer.

Cruise is fully integrated into the ECM on these trucks from 94+. There isn't a cruise control module anywhere or a cruise servo.

Besides faults, it's going to be a brake switch (there is a code for this) or the stalk on the steering column.

J

[zero76c]

hello could you tell me what is the stalk you talk about is that the turn signal controls
thank you
thomas

[Robyn]

The STALK is the column assembly.

The best action is to scan the thing.

Trying to "manually" wring this out is pretty sketchy at best.

Check the ECM for codes before doing anything else.

The ECM controls the fuel injection pump and therein the cruise as well.

Even some small error can disable the cruise.

Once you get an all OK on things via a good scan, then the system can be wrung out.

With things OK the scan tool will show if the cruise control is being activated or not and from there things can be diagnosed.

This truck is an OBD2 SYSTEM and you just can't do much of anything without a top notch scan tool.

Ahhhh, question.

Is the CHECK ENGINE LAMP ON ??

Does the lamp come on when you turn the Ign. on ???

Does this truck have an auto or manual tranny ??

If the Check engine lamp does not come on with the Ign. then possibly the bulb has been removed or is not working.

A cheap way to get info is to go to an Auto Zone store and have them scan for codes.

If you get any, let us know and we can advise from there.


Keep us in the loop.

Robyn

[zero76c]

hello will the fact the abs light is on keep the cruise control from working and thank you for any suggestions

[Robyn]

Yes, this very well could kill the cruise control.

The ABS is integrated into the entire system on the OBD 2 and with it in a "Error" mode the cruise is likely not going to work.

Pull the codes on the ABS and find out what's bothering it.

Good bet that once the ABS is happy the cruise will work again.

So, get the ABS sorted out and go from there.

Hopefully it's a simple thing like a wheel sensor.

Good luck

[zero76c]

where do i find the code i have a reader but it does not show any code when plugged in lmk
thank you

[john8662]

Had a truck in the shop this week that had no cruise control and trouble locking the torque converter.

Scan tool worked by manually locking the converter which told me the trans was fine.

Ended up being the brake switch. The switch controls several circuits independently (multi pole multi throw).

Brake lights still working fine on this one.

Anyways, replaced switch which solved the converter locking and now the cruise works as well, previous to the trans issue it was just the cruise that didn't work.

Be careful with the clip that holds on the switch to the brake petal assembly. It's hard to get off, takes two small flat blade screw drivers. It's a special clip.

Hope this helps.

[Hal StClair]

A code will disable the cruise for sure. If someone installed LED's in the brake light circuit the PCM won't like it and will kill cruise. If you have ANY voltage on the brake light switch (going to the lights), bad brake light switch, wires in trailer harness, etc the cruise won't function. Even something as small as a half volt will kill it. They can drive you crazy for sure.
Hal

[zero76c]

have a 2000 gmc 6.5 diesel and is leaking engine oil out and around the bumper i am going to say it is either the cooler or lines i am leaning towards it being the lines how bad of a job are they to change would someone lmk
thank you

[Robyn]

Could be either the lines or the cooler, but likely the crimped end on the lines.

Get the grille out and see wasssssup in there.

Not all the bad to change.

The stock/factory ones will slide right in fairly easy.

The fittings at the block (if stock) are a slip in o ring connection with a E ring that holds the line in.

With the age I would plan on replacing the fittings with new ones.

If you use all factory parts its a snap.

Thread the fittings into the block and then lube the line end and shove it into the fitting.

The E ring snaps behind the flange on the hose end and its good to.

NOTE
The E ring is assembled in the fitting, leave it there and the line will snap right into the fitting.



There should be a bracket right below the LH front motor mount that carries the lines and secures them from wiggling around (A must have)

The other option is an aftermarket line kit that uses the stainless braided hose.

The cooler must be in the loop on these engines for proper oil flow


Once the grille is out that area is easy to access.

You can remove the upper and lower fan shroud to get a load of room in that area to wrangle the lines.


Good luck

[Drillman]

Had this happen recently on my '97 and it turned out to be PMD on the way out. Replaced with old unit I had in the toolbox and straight away had criuse back.

[rustyk]

I have the Innova 3100 OBD2 code reader, and it's loaded with features, including ABS. It's not cheap, but its ease of use makes it worth it. I was going to get the cheapo Harbor Freight unit, until I found out it wouldn't read my van.

With newer vehicles, a code reader is as essential as a socket set.