Guys, my first technical assist shout-out.

My '86s cruise is not working. I have tested the pink/black coming from the fuse box and she's got 12v. The switch wiring was all tested with my ohmmeter and it's all good. On/Off, R/A, and Set buttons all work fine. In addition, with the harness connected to the turn signal switch, I have 12v at the double blue that should send voltage to the connector which mates with the servo.

At the servo connector, I have nothing. No voltage at all at any wire. No 8v between B and D.

Everything looks good. The factory harness seems to be intact and it seems to be a pretty direct run from under the hush panel through the firewall block to the servo. I do have a FSM and have looked at the diagram.

Any assistance would be greatly appreciated, thanks!

Edit: Looks like the wiring from the stalk switch then goes to the instrument panel, where it then travels to the servo. Wuh oh...now I'm in trouble. I really want this to work....but I am nervous about yanking that panel.....

 

stop lamp/release switch/s ? I believe it also runs "through" the cluster for VSS etc!

 

So a brake switch issue will cut ALL voltage to the servo?

 

The brake switch and associated wiring tests out fine. 12v at the blue wire, resistance to 0 when jumping across the cruise terminals with the the brake pedal up, infinity when it's depressed. Jumping blue to gray with the cruise switch engaged- still no action at the servo. The servo is just receiving no current across B and D no matter what. My speedo and the entire cluster have no issues, everything else works perfectly. And the servo checks out perfectly as well.

 

This pretty much has to either be in the cluster's cruise module or the wiring between that and the servo, no? C'mon experts throw me a lifeline...

 

In order for the cruise control to engage, the vehicle must
be going at least 25 mph. You will only see a feed back
signal on Pin B and D when the servo motor moves.

To verify the cruise control servo motor is working do the
following.

**************************************** ************
Unplug the 5 pin connector at the cruise control servo
above the battery area. It has a locking tab high up
on the connector.
**************************************** ************

You need 3 jumper wires.
Jump the pins at the cruise control servo module and
not the disconnected 5 pin connector.

The 5 pins from left to right.
A=(Dark Blue wire) 12 volts for vent valve solenoid.
B= (Tan wire) servo is feedback to cluster
C= (Black wire) ground
D= (Dark Blue/White wire) is servo feedback to cluster
E= (Light Green wire) 12 volts for Vacuum solenoid.

Connect a jumper wire from the negative terminal of the
battery to Pin C which is ground for both the vent valve
and vacuum solenoids.

Connect a jumper wire from the positive terminal of battery to pin A . This closes the Vent valve solenoid. You should hear a clunk sound as the solenoid closes.

Start the engine and let it run for 1 minute.
Shut engine off.

Take a jumper wire and apply 12 volts from the positive
of the battery to Pin E.

The vacuum solenoid should pull the throttle body to
wide open.

Remove the wire from Pin E.

The throttle should stay pulled at wide open throttle.

To verify the vacuum vent switch works, press on the brake
pedal. The throttle cable should retract.

If the test fails, look at the bottom of the cruise control
servo. There are two vacuum hoses. One goes to at T fitting
and goes to the vacuum ball below the left front headlight
motor. Vacuum I believe comes from the rear passenger side of the plenum and goes to a check valve with two
outputs. One output goes to the interior of the car and is used for the vacuum vent actuators for the HVAC. The other output goes to the round vacuum tank used for cruise control

You'll have to verify vacuum is present and there are no hose leaks.

 

Hooked: Great troubleshooting procedure; my cruise on my '86 isn't working either; I did the resistance measurements per the FSM on the servo and all checked out OK; my vacuum tank was missing, and the vacuum tee was plugged off at the tee fitting by the left front wheel; I just purchased a replacement vacuum tank and check valve, so we'll see if that gets me going; if not, I will follow your procedures and see how I make out........

 

Thanks. All of the troubleshooting articles I have read so far indicate that there should be 8 volts measured across B and D of the harness with the key on and the stalk switch on. I don't have that. And all of them also say I should hear the solenoid click when I turn on the stalk switch. But I am going to go through your procedures because they just make a lot more sense to me. I appreciate the reply very much.

Between you guys and the FSM, I am on good footing. Forget the K&N filter, C4 noobs- buy the FSM as your very first purchase.