Cruise COntrol gets a new life

[LMP]

Cruise inoperative for almost 2 years…decided to go for it. First checked for easy items, brake pedal kill switch….contact found somewhat erratic, but after correction, proved to no avail . So checked for operation of servo control. Tried to operate the servo by applying 12V directly to solenoid valves, thus bypassing the ECU; servo itself proved inoperative. Both solenoids need be fed 12V at same time in order to apply vacuum. But then, applying 12V to 1 solenoid at a time would yield a definite clicking sound from one, and total silence from the other, although the electrical circuit was proven OK. I concluded one of the solenoids was mechanically blocked.
Dismantling the servo unit is not complicated, as all parts come off one after the other simply by removing the screws (small torx needed). You must be careful; remove parts very carefully, as there are several little pieces you want to keep in control and notice the way they were assembled.
Indeed, the “vacuum apply” servo valve was blocked with rust from moist air sucked by the system . It was quite simple to dislodge blocked plunger from solenoid, clean out , apply a drop of WD40, reassemble, then test electrically for operation (both solenoids clicked now), then apply vacuum from car and activate the bellows from direct 12V to solenoids. Operation all right. reinstalled back in car.
Needs be proven on the road now….will do within a few days.
Will post pictures of dissassembly and short video of bellows operation once home in town with wide band internet (slow dial up speed at cottage does not allow for that).
..mmm..one part was lost during the exercice....this little clip that keeps the throttle cable from escaping the servo unit. YOu try to remove it with care...then pop...gone nowhere to be found. I tried to find a replacement, wandered all around the place....and just by accident, I found, you know, that little plastic tab they use on bread loaf bags to keep them closed....well, it slipped tight on the attachment and clicked perfectly in place; tested cable to certify it would stay there, with flying colors....so good for all the time I wondered what use could there be for these plastic contraptions....that is reclycling, yeah!

[Meridivs]

Very interesting post! I have a similar problem with one of my TS and, with the help of some pictures, maybe we can fix it.

Keep up the good work Looking forward for the pictures/video..

[LMP]

CONfirmed operational.
This applies to '93 3.8 and similar
Diagram www.avigex.ca/xport/cruisecontrol.jpg shows solenoid control in released state. Vacuum on left and vent on the right. Vent is "vented" when released meaning it must be actuated to contain vacuum when vac control is applied. Contacts are E(vac) and A(vent), with C as common ground. B and D are for the variable reluctance position transducer.
Next picture www.avigex.ca/xport/DSCN1216s.JPG shows dismantled servo unit with vacuum side solenoid . plunger was stuck in solenoid
www.avigex.ca/xport/DSCN1217s.JPG shows vac solenoid assembled and vent side parts in sequence.
www.avigex.ca/xport/DSCN1225s.JPG shows assembled unit connected to vacuum source (not visible) and wired for test, with 12V applied to A and E, and ground applied manually to C. Bellows shown collapsed.

www.avigex.ca/xport/DSCN1227.MOV (quicktime, 3 megs) shows servo unit in operation as ground is applied, then removed.

[Meridivs]

Excellent post!

I wish I had the 3.8 :

Anyway I'll look for it in the Repair Manual and similarities in my 3.1 setup.

Keep up the good work & that TS rolling

[Escoffier]

Bread bag clip.....................That is outstanding!!!!
Goes to show what an active mind can accomplish. LMP, thanks for your posts, you and JRS3800 helped me get my 95 TS 3800 running.
When I get time I will now have to look at my own CC.