Cruise control module question

[ramonesfreak]

1983 911SC

I replaced the cruise control cable with a new one last year. CC was working fine.

Today on highway, with CC on, there was some minor surging up and down, a few MPH at most. Turned it off and on at the stalk switch a few times and then it died completely...

Stopped and bought a multimeter - Klein MM400

I have never used a multimeter and have never tested any electrical system. I have no idea how to do this.

The Bentley test procedure as usual is too vague for me. I pulled the module out of the car but I am not certain where to put the test leads. For example, when it says "Connect ohmmeter between terminals 3 and 7" what does this mean? Doesn't the black MM lead need to touch ground/chassis? That leaves just the one read lead...how do I connect between terminals?

Does the test procedure happen at the car with the key on or can I test the module at work bench?

Can anyone walk me through the basics of how to connect the MM to the module (or is it the harness or both) that Bentley as usual skips and has no photos for?

Also, does the symptom I described with the surging happening right before it died lead you to believe it is the module or is that an obvious symptom of one of the other components?

The cable is brand new and was working. The vacuum hoses are connected. #6 fuse at the trunk fuse panel looks fine.

Regarding repairing the module, I am ok with a soldering iron and if the two big caps are leaking I can probably replace them myself. How do I open the module? Do I bend the metal tabs and slide out the board? Is there a best way to do this without breaking anything? The metal looks pretty thick so I dont want to crack the plastic part of it

Lasty, if I cant fix this, who is currently recommend to rebuild these?

Thanks

[ammonman]

You need to set the multimeter to read ohms of resistance (should be a Greek letter Omega showing that setting on the meter), not voltage, and take the measurements indicated by touching one probe to each of the terminals indicated in the procedure. No need to have one probe grounded to the chassis unless the test procedure indicates this.

[ramonesfreak]

thanks


regarding getting it apart, that was easy. soft metal.

The board looks almost new. I dont see any leaking or cracks but will use my high powered magnifier glasses to check

[ramonesfreak]

Originally Posted by ammonman

You need to set the multimeter to read ohms of resistance (should be a Greek letter Omega showing that setting on the meter), not voltage, and take the measurements indicated by touching one probe to each of the terminals indicated in the procedure. No need to have one probe grounded to the chassis unless the test procedure indicates this.

still not clear so when it says "Connect ohmmeter between terminals 3 and 7"

does that mean one lead goes to 3 on the module and the other lead goes to 7 on the module or is one terminal on the harness and the other on the terminal at the module?

does it matter which lead, red or black, goes to terminal 3 and 7 or no?

[Richard Knight]

When measuring resistance it doesn't matter which way round the test leads are.

[ramonesfreak]

ok thanks

update: after looking at module and thinking it looks pretty good but noticed some slight corrosion on the terminals, I cleaned them and hooked it back up and went for a ride for about 40 miles of highway and the CC worked very well. played with the stalk lever on- off- accel- reset etc...and CC did not die. Functions all worked. I guess a few more test drives before I decide this was the fix but I think for once I lucked out.

[mysocal911]

Originally Posted by ramonesfreak

thanks


regarding getting it apart, that was easy. soft metal.

The board looks almost new. I dont see any leaking or cracks but will use my high powered magnifier glasses to check

Unlikely you'll ever see them! Just re-solder the complete board.