I've gotten pretty deep into trying to fix my cruise control and I've read countless threads to no avail, so I thought I'd try here as a last-ditch effort to get some useful info. Any help would be much appreciated...

To test the components of the CC system, I've performed the following tests per the instructions below popularly circulated online. All tests have the specified outcome (everything is working - and yes, my vacuum hoses are brand new...) except for the speed sensor test - when I connect a voltmeter to pins 8 and 11 I get around 8.5-9 volts no matter what speed I'm going. I've read on some other threads that people have gotten a similar result but nobody has any explanation why. I have a hard time believing my speed sensor is faulty, because my speedometer works fine, and as I understand they both get a signal from the same sensor. Am I doing something wrong or using my voltmeter incorrectly? Or does anyone know what my issue could be? I have also replaced the CC ECU with a known working (supposedly...bought in "tested" condition on eBay) unit and it's still not working...I suppose it's possible I got duped on eBay, but the solder joints on both ECUs I have look fine.

Another question I'm curious for an answer to: Does anyone have a working cruise control on their D1 that they have not converted to a D2 cruise control ECU?

Ground Test - From pin 8 (black wire) on the cruise control module plug perform a continuity test to good chassis ground.
Main voltage test - With ignition & cruise control system on (on-off switch on the dash), transfer in high (non difflock) & auto box in 'drive' (you do not have to turn the engine on, just press the brake pedal and shift the gear) connect volt meter between pin 8 (black wire and if difficult, you can connect it to any ground) and pin 10 (white & yellow wire) you should have battery voltage, if not check fuse, under the steering wheel following the diagram there.
Secondary voltage test - Connect volt meter between pin 8 (black wire) and pin 9 (Purple & Green wire) you should have battery voltage if not check lock out relay or gear selection switch.
Brake Pedal Test - Connect volt meter between pin 8 (black wire) & pin 5 (green & purple wire). Press the brake pedal, you should get battery voltage.
Steering Wheel Set / Accel Test - Connect volt meter between pin 8 (black wire) & pin 3 (red & white wire). Press the Set / Accel button, you should get battery voltage.
Steering Wheel Res / Decel Test - Connect volt meter between pin 8 (black wire) & pin 4 (blue & white wire). Press the Set / Accel button, you should get battery voltage.
Vacuum Pump Test - Using a jumper wire connect pin 10 (white & yellow wire) to pin 1 (white & blue) this provides power to the pump. Then using a jumper wire connect pin 6 (black & yellow) AND pin 7 (black & red) to pin 8 (black wire). This should energise the pump & solenoid and the bellows (rubber activator on top of the engine) should contract.
Speed Sensor Test - Connect a volt meter between pin 8 (black) and pin 11 (yellow & pink), drive the car around the block, voltage should increase as speed increases.

 

I "had" a working Lucas prince of darkness C/C ECU on my 95 D1. However it worked 3 times & is now dead. D2/P38 Hella C/C ECU is the way to go. Other units were hit or miss new, but good luck finding a working one these days.

 

Have you checked the vacuum pump motor by hand to see if it even turns?

 

I have performed the vacuum pump test as stated above, and the pump turns on and the actuator contracts just fine.

Yeah I'm thinking maybe all of these D1 CC ECUs have bit the dust by now...The D2 ECUs are cheap enough on eBay so I suppose I'll give that a try before I look into the speed sensor thing any more...

 

Just make sure to get the D2/P38 pigtail with the Hella C/C ECU which makes things much easier.

 

Yep, thanks, just ordered one - I'll give an update on how it goes once I have the time to do the procedure here in the next week or 2.

 

Wired in the D2 ECU and the cruise control works like a charm - thanks again. This is definitely the way to go instead of trying to repair or find and old D1 CC ECU...

I'm sure when I was checking the speed sensor previously I maybe should've been using AC volts instead of DC...