1G 91+ Cruise Control? In 2025?

[CrackedDSM]

Cruise control isn't setting or activating. It's a 91 module, in a 91 DSM. The Cruise control switch on the pedal makes full contact, the stalk light lights up amber when you turn it on, but it acts like it doesn't wanna turn off. The button to set cruise does nothing. No Green light on the cluster, nothing. All fuses are fine.


What else can I check? The vacuum line connecting the vacuum pump to the canister is connected with no breaks or etc.

Does the clutch switch that prevents the car from starting work in conjuction with cruise control or is that separate completely? Is there a way I can test the pump or the cruise module itself?

Is there anything with ECMLink I can log or test with?

 

[UKNOWHO]

Hey whats up i read your post, you made me dig out the old electrical service manual. Now mind you my car is 1992 and so is my service manual. But the first diagram shows the circuit def needs the clutch switch. The one at the top that is used for nlts. The lower one is neutral safety which i dont think will cause your issue. Attached pics for you to reference.

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[CrackedDSM]

Hey whats up i read your post, you made me dig out the old electrical service manual. Now mind you my car is 1992 and so is my service manual. But the first diagram shows the circuit def needs the clutch switch. The one at the top that is used for nlts. The lower one is neutral safety which i dont think will cause your issue. Attached pics for you to reference.

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Well, there are two. That one that's pictured is plugged in and working.

There's another one opposite of the one in the FSM near the firewall that I have unplugged. It's only for starter activation, but IDK. I may plug it back in and try it all out again just for giggles.

But, I think it's either my stalk(the amber light will not turn out once you've activated it) or some kind of wiring BS. Or something else that's dumb. Lol. I thankfully do have an electronic copy of the FSM on my computer.

 

[CrackedDSM]

If the green cruise control light never comes on…is that a clue? Like if it was just a bad vacuum line or something wouldn’t the light still come on?

 

[miliman13]

I’m probably wrong but my understanding is that the reason why my cruise control doesn’t work is because I have the clutch switch unplugged (the same one we all unplug to avoid thrust ware )

Plug it in and check.

 

[CrackedDSM]

I’m probably wrong but my understanding is that the reason why my cruise control doesn’t work is because I have the clutch switch unplugged (the same one we all unplug to avoid thrust ware )

Plug it in and check.

Worth a try. If it's a magic fix then I'm gonna put a toggle switch inline so I can start the car without the clutch pedal, and just flip it on for cruise control operation.

 

[CrackedDSM]

Plugged the other clutch switch in, no fix. Have a new stalk/combo switch on order.

 

[steve]

The system will tell you a lot if you know how to ask it.

91 - 94 DSM Auto Cruise Control Diagnosis

 

[CrackedDSM]

The system will tell you a lot if you know how to ask it.

91 - 94 DSM Auto Cruise Control Diagnosis

Thank you Steve, I will do this.

But, IDK if I can do it right now. The CC stalk/amber light will not actually turn off. If I tap the brakes SOMETIMES it'll turn off but eventually the stalk kind of turns the light back on by itself within a few moments. I'll throw the new stalk in when it arrives. If it still doesn't work then hopefully it'll allow me to pull codes.

I should've expected this but I admit I'm a little surprised. Everything else with the car just kind of worked when I plugged it back in(stereo, A/C, etc). The CC in these cars seem a little...over-engineered...to put it lightly.


Can I ask a question to you though, if there was a crack in the vacuum line or something like that, would the green CRUISE light on the cluster still come on? Or does it only come on when everything works?


Edit - I just realized something. I am simulating my idle switch operation in ECMLink. I do not have the idle switch physically plugged in to the harness. Would this have ANY effect of Cruise Control operation? Is it enough that ECMLink simulates it?

 

[steve]

Is it enough that ECMLink simulates it?

I don't think so. IIRC, the Cruise Control has connections to the TPS and IPS. I double checked, the CC docs (32 pages worth) are at the end of the Fuel System (14) in the Engine/Chassis/Body FSM (Vol 1) and it shows that the Auto-Cruise Control Unit is connected to them simulating only works for ECMLink internally. The CC is also connected to it's own clutch switch, the VSS, and the stop lights.

 

[CrackedDSM]

I don't think so. IIRC, the Cruise Control has connections to the TPS and IPS. I double checked, the CC docs (32 pages worth) are at the end of the Fuel System (14) in the Engine/Chassis/Body FSM (Vol 1) and it shows that the Auto-Cruise Control Unit is connected to them simulating only works for ECMLink internally. The CC is also connected to it's own clutch switch, the VSS, and the stop lights.

I have been going through the FSM myself and stumbled upon that same thing. I'm gonna plug it in and go test the system again. Can't hurt to knock another thing off the "check it" list.

 

[CrackedDSM]

Update: No, it did not make a difference. Sad day.


It's still so weird to me how the stalk's amber light will not turn off unless I hit the brakes. If I hit the brakes, it turns off. When I let off brakes, amber light turns back on.

 

[Tyeler18]

The light on the stalk should have nothing to do with the brakes, I imagine it's breaking contact from vibration and thats the only reason it's doing it. The amber light just means that the "on" portion of the stalk is working. The black/white wire feeding the stalk 12v is working if the light is coming on. You can test the functionality of the set and resume buttons by testing the yellow or red wire coming out of the stalk. They will have 12v on red while pressing set and 12v on yellow while pressing resume. The fact that the bulb wont shut off or intermittently does leads me to believe the stalk itself is acting up but that doesn't mean the button side of it isn't working and I'd definitely test that to be sure they're working because if they are the bulb is somewhat irrelevant. The green light on the dash also wont light until the system is active so that likely eliminates any mechanical issues with anything under the hood since it should at least try to activate.

I dont know if the idle switch does matter, but should be easy enough to trick by just grounding the wire and eliminating the pin from the ecu connector so it's only function is for cruise control. This would eliminate the idle switch completely from the circuit, although I don't exactly know what function it has in the ecu but I assume it's currently unhooked so grounding it will simulate the other side of it's functionality. Also make sure you have 12v on the blue/white wire at the brake switch as well as the blue/orange wire, you should lose 12v on blue/orange when stepping on the brake pedal. It's honestly a relatively simple setup on these, or you can do what I did and toss all that cable garbage out and install a haltech with DBW and enjoy the wonderful functionality of a modern DBW cruise system using the stock cruise stalk

 

[97egl]

I have working cruise on my daily which is also a 91 so I can verify that it will still work with the idle switch unplugged.

Also I have my clutch safety switch bypassed so I can crank without pressing the clutch and my cruise has always worked fine.

 

[CrackedDSM]

I have working cruise on my daily which is also a 91 so I can verify that it will still work with the idle switch unplugged.

Also I have my clutch safety switch bypassed so I can crank without pressing the clutch and my cruise has always worked fine.

Awesome. Appreciate the insight.

 

[steve]

Also I have my clutch safety switch bypassed so I can crank without pressing the clutch and my cruise has always worked fine.

Aren't there two switches on the clutch pedal, one for the CSS and one for the Cruise Control?

 

[CrackedDSM]

Aren't there two switched on the clutch pedal, one for the CSS and one for the Cruise Control?

Can confirm, there are two on mine. Closer to the driver is the cruise control one, and on the opposite side closer to the firewall is the CSS/starter interrupt.

 

[steve]

Thanks, Verification is helpful when you reach the point where you think you remember something but it's been a few decades since you last looked.

Could you come and find all the tools I've lost? I know there here somewhere.