HELP! Cruise control/Brake "Isolation Valve" issue

[Russell Dubuc]

Hi, I seemed to have mistakenly posted this issue the other day in Sport Track but I believe it belongs here. Apologies, first time on this forum...

Problem: with Cruise Control on and then applying brakes, CC does not immediately release/turn off and usually (the scary part!) accelerates to compensate until you apply more brake pressure, then it releases.

So someone from my online search believed the brake "dump" valve, or I think more properly called the Isolation Valve is sticking and thus not sending out a brake application/CANCEL CRUISE signal accurately. I don't see an isolation valve as shown on other models/years, all I can see is a gigantic ABS control unit under the battery with all the brake lines going in and out and a very large processor with a boatload of wires. Is the problem somewhere inside this unit or elsewhere? I need any help I can get please. In the meantime, I'm going to check for TSBs or recalls on this.

Thanks,
Russ in Maine

 

[swshawaii]

SPEED CONTROL DEACTIVATION SWITCH
http://www.phila.gov/fleet/Warranty Recalls/Recall 09S09.pdf

 

[Russell Dubuc]

Yeah, so further research has pointed out this switch and it's issue but dealer already changed this five years ago.

I got a new one from AutoZone...it worked spectacularly for about a week, then holy crap! IT'S DOING IT AGAIN!!!

So, really hoping I got a bad aftermarket switch, I got ANOTHER ONE under warranty from AutoZone that I'm going to try out today.

Question is...
Is this switch the ONLY POSSIBLE CAUSE for this issue? What if this (actually the FOURTH) switch does the same thing? If this doesn't permanently fix this, THEN WHAT???

 

[Drewmcg]

Could be other wiring problem in the engine compartment. Any mice chewing in there? Any illuminated brake, anitlock, or CIS lights?

 

[Drewmcg]

by the way, what's an "isolation valve"?

 

[Russell Dubuc]

Re: "isolation valve", I just used that term I read somewhere else. I'm thinking he must've meant the cruise deactivation switch which btw, is labeled an "interrupted switch" on the Duralast (AutoZone house brand) box.

So anyway, guess what? Just as I was expecting, the NEW new switch didn't solve the issue...it did it again this morning.

I did scan the processor for codes, nothing came up.

 

[Drewmcg]

It doesn't sound like a deactivation switch issue in the first place. Sounds more like a shorted wire on the second connector down to pcm (2002) or bad control button on steering wheel. I have a similar issue (mice chewed wires) and tried changing the motor that connects to the speed control throttle cable (from donor vehicle) and no joy. Not worth fixing IMHO.