cruise control not working: suggestions?
Race Car
Joined: May 2003
Posts: 4,260
Likes: 105
From: SoCal
"I am willing to bet money that the original servo failed because of a cold solder."
There's nothing really in there but; a motor, a solenoid, & a feedback pot.
Hardly your typical unit with potential for cold solder joints.
There's nothing really in there but; a motor, a solenoid, & a feedback pot.
Hardly your typical unit with potential for cold solder joints.
Rennlist
Lifetime Member
Lifetime Member
Joined: May 2001
Posts: 3,651
Likes: 8
From: Chino hills, CA
Loren,
Both units that I repaired had cold solder joint at the through hole soldering on the PCB. Exact same issue with a cab top controller repair I did not too long ago.
Please understand that I am not trying to start a auto electronic repair business, I have no interests. I did all the repairs for free, just helping out another Rennlister.
Both units that I repaired had cold solder joint at the through hole soldering on the PCB. Exact same issue with a cab top controller repair I did not too long ago.
Please understand that I am not trying to start a auto electronic repair business, I have no interests. I did all the repairs for free, just helping out another Rennlister.
Race Car
Joined: May 2003
Posts: 4,260
Likes: 105
From: SoCal
"Both units that I repaired had cold solder joint at the through hole soldering on the PCB."
The point is to not mislead Rennlist members into thinking that the actuator is a high falure rate type of unit.
The cruise ECU itself has a higher failure rate which is still very low overall.
That actuator is not only used by Porsche but also by Mercedes Benz, i.e. last 25 years, which basically never fails too.
The point is to not mislead Rennlist members into thinking that the actuator is a high falure rate type of unit.
The cruise ECU itself has a higher failure rate which is still very low overall.
That actuator is not only used by Porsche but also by Mercedes Benz, i.e. last 25 years, which basically never fails too.
Drifting
Joined: Jul 2007
Posts: 2,373
Likes: 3
From: Fairfax Virginia
"Both units that I repaired had cold solder joint at the through hole soldering on the PCB."
The point is to not mislead Rennlist members into thinking that the actuator is a high falure rate type of unit.
The cruise ECU itself has a higher failure rate which is still very low overall.
That actuator is not only used by Porsche but also by Mercedes Benz, i.e. last 25 years, which basically never fails too.
The point is to not mislead Rennlist members into thinking that the actuator is a high falure rate type of unit.
The cruise ECU itself has a higher failure rate which is still very low overall.
That actuator is not only used by Porsche but also by Mercedes Benz, i.e. last 25 years, which basically never fails too.
Three Wheelin'
Joined: May 2001
Posts: 1,720
Likes: 7
From: Birmingham, AL
I have had cruise control fail on many cars...it has always tuned out to be a switch. There is a switch that indicates the brake in pushed, and a switch that indicates the clutch is pushed...check those...I bet one of them is sticking. I don't know exactly where they are on a 993...but in my experience, they have been actuated by the brake or clutch pedal...so look at the bottom of each those pedals for a switch...if it's very quite...you can probably even hear it actuate.
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Rennlist Member
Joined: Nov 2013
Posts: 2,717
Likes: 620
From: Minneapolis
Went through this last summer. Ended up being the control module under the passenger's seat. I got a replacement from an R lister for $ 100 bucks- plugged it in and works perfectly. These modules ARE known to fail. Why? who knows. The good news is this module ONLY controls the cruise so while there's no other systems effected, it can be difficult to diagnose. I'd try the switch first as recommended, but this may be your culprit.
