Cadillac Owners Forum banner

1 - 4 of 4 Posts

·
Registered
1987 DeVille
Joined
·
4 Posts
Discussion Starter #1
Greetings,

So I'm getting codes about the idle speed control circuit.
I pull off the isc motor/switch.
I find that the switch works, but works reverse to what I thought it should.
I put it back together and read up on that circuit.
I take it back off, days later, and check it again and it works normally and reverse and every other way. In fact, The switch would be on or off at random when the plunger was in any position.

So since it can't get much worse, I take it apart.
The plunger is threaded and a gear spins on the threads to move the plunger in or out. The gear is of course driven through other gears by the motor.

The bottom of the driven gear are slip washers which ride a round lever affair which activates a switch. There is a spring on the bottom of the plunger and holds the plunger up.

So, in idle, the plunger is pushed which pushes the gear which pushes the lever affair which activates the switch.

Did I loose you, Yet??

Anyway, the contacts in the switch portion are mounted to a flat copper spring. the flat copper spring had broke {from flexing I imagine} and was loosely making contact at random.

I called the part broke/unfixable and put it back together and on the car{without the broken contacts} and now the ecm is wondering why my car is never in idle.
 

·
Registered
1987 DeVille
Joined
·
4 Posts
Discussion Starter #3
It is my hope that I may help another by relating my experience with the isc motor/switch. I tried to explain that the switch tested good, but, was in fact, intermittently good and bad. Only by dismantling the part, it became apparent what the problem really was. Thank you, for caring and trying to solve my problem. There are a number of things going on with this Deville and we are delighted "new" 87. We have little money for parts, no money for labor, and must take our time to understand what she is supposed to do. Then we can understand what she is not doing or not doing correctly. I am moving on to the cooling fan circuit. The previous owner has bypassed the fan control and ran the ground side from the fans straight to ground. I am pulling up codes on that too. I imagine the feedback to the control module is not what it wants to see.
Thanks again.
 
1 - 4 of 4 Posts
Top