Cruise control issue

[theexbrit]

Hi all,

 

my ac was working fine but now suddenly each time I switch it on the green "Cruise Control" light on the dash flashes on & off & the cruise won't engage. I haven't tested anything yet, just seeing if anyone has a simple answer first.

 

Thanks.

[Towncivilian]

The FSM wants you to begin with page EL-170 of the factory service manual. But first I'd check that your horn works (if not, fuse or spiral cable is likely to blame), ensure the ASCD pump's vacuum hose is not damaged, and that the rubber bumpers on your brake pedal are still present. If that doesn't yield any fix, then continue with the electrical diagnoses in the FSM.

[Alkorahil]

So.. AC comes on fine. Cruise control works fine, but cruise truns off when AC is turned on.

 

When you have the cruise control on, and then turn on the AC system, the ECU wants to raise the RPM of the engine to keep the vehicle at the set MPH because the AC system creates a drag on the RPM of the motor.

 

 

 

 

 

There is an input or sensor not giving input or proper input to the ECU, so it shuts the cruise control off. It may be a revolution sensor on the transmission or speed sensor on one of the wheels giving intermittent input. This will require a lot of troubleshooting.

 

Is there a check engine light on as well?

 

Can you have AC on and then engage the Cruise later?

 

 

[theexbrit]

I'm sorry guys I messed up. It has nothing to do with the ac, it's just the cruise control that's acting up, I don't know why the heck I mentioned the ac!

[ahardb0dy]

So now when ever you turn the cruise on the light just blinks?

 

As was said previously, Check the rubber bumper on the brake switch, if it disintegrated the system may think you are stepping on the brake and will not engage.

[Alkorahil]

Ok then do what aHardbody said! Probably is that simple!!! I am glad to hear that as well, the AC issue you originally described had me thinking 'replace ECU' would be the final answer to fixing it.

 

 

 

Replace the rubber bumper for the brake switch at the same time.

Here are the part numbers:

 

46512-H0101

RUBBER-STOPPER, BRAKE

 

46584-S0100

RUBBER-STOPPER, ASCD

[Towncivilian]

When my cruise cancel bumper fell off my cruise still turned on, it just didn't set (nor did the "set" indicator blink, that may have something to do with the fact that I replaced it with an LED bulb but I doubt it). But it is still worth checking, your 96 may be different after all.

[theexbrit]

Thanks guys & thanks for the part numbers A, I'll check out the rubber bumpers tomorrow.

[ahardb0dy]

it's a good place to start, If you have a manual tranny or even if you don't having a couple of those bumpers in the truck is a good idea, if the one for the brake lights falls out the brake lights stay on, easy to just pop a new one in, same with the clutch switch that won't allow the truck to start if it falls out, yes you can reach down and press the button to get it started and make it home but just as easy to pop one of the extra one's in.

 

Also check the vacuum line going to the cruise control pump thingy under the hood

[Alkorahil]

Agreed! the stoppers are old anyways and ready to blow up on you, they tend to last about 12 years then explode, or so It wont hurt to eliminate that possibility.

[theexbrit]

I checked the stoppers & they both seem ok, but I'll get a couple of spares anyway. I'll see what I can find using the FSM.

[ahardb0dy]

Did you check the hose under the hood going to the cruise actuator pump?

[theexbrit]

I had a brief look & it seemed ok. I was thinking today that I've been messing around under the drivers kick panel doing some rewiring, from the FSM it seems that the ac control unit is there so I'm wondering if I damaged something. I'll check it out in a day or two.