I have a 1991 Range Rover which I bought 16 months ago. The Cruise Control has never worked for me. When I started to investigate this I realized the Cruise Control (CC) relay was missing. I replaced it but found no difference in the operation of the CC. The vacuum pump itself works and the vacuum lines are good. I realized today that when I installed the new relay the fuse blew. As soon as I replace the fuse and turned on the ignition it blew again. I removed the relay, renewed the fuse and turned on the ignition without the fuse blowing. Does anybody have any idea what’s going on?

Thanks, Dan

 

Without it being an obvious or difficult-to-trace direct short between CC voltage supply wires,
it sounds like one of the following has failed.

1) Diodeto the Neutral Lockout relay.

2) Steering wheel ribbon cassette:
A)connectionfailure (gone short)
B)Wires from it to steeringwheel buttons chaffing large metal nut.
C) Wires from rear of cassette past ignition barrel etc short/chaffing metal.

3) Vacuum Pump ( motor may spin, but is the solenoid faulty! )

4) Speed transducer related short.

5) Wrong relay! or relay socket wiring failure.

6) Cruise Control ECU failure.

Does fuse blow when CC "Highway" switch is disengaged before ignition is switched on?

Try unplugging everything to do with CC,... (Vacuum pump, steering wheel connections at rear of ribbon cassette, ECU, Rear of "highway" switch ,...& of course, the Relay), replace blown fuse, switch on ignition,= does fuse blow? - Yes... take RR to auto electrician.... or live without it!
if Fuse did not blow -....

switch OFF ignition,plug in relay - ignition ON = Fuse blow? Yes/No???
If Yes, check all wires & connections to & from the relay.
If NO....Switch off ignition, add one more thingthe circuit, - Ignition on = Fuse blow Y/N??

If YES - Item you connectedor something connected to it is at fault. Investigate.
If NO - repeat procedure.
keep adding one item at a time to the CC circuit &the fault should reveal itself.
- the ECU is usually a damage victim in these issues,but you must be sure theECU did not cause the failure, as plugging in a replacement may just blow again you see! that is £££ down the drain!!!

Good luck,

I hope it is not as time consuming as my CC problem!
- I had multiple failures & that made it harder to track down

I fixed my cruise control in the end though &man is it worth it!!!

Put a lot of time aside for this one! - just in case!

 

Thanks for the advice. I did not have the cruise control "Highway" switch engaged when the fuse blew. I'll start tracking this stuff down as soon as I figure out why my check engine light keeps coming on.

Dan