Cruise control relays - D1

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dhuddleson

Well-known member
Apr 21, 2004
128
0
Ottawa, Ontario, Canada
Cruise control relays - D1 - Now test ECU ???

The cruise control for the Discovery I has two relays, a "green" one and I think a "yellow" one. Can anyone tell me what type of relays these are? I am trying to determine if they are SPST (ie. OFF or ON) or if they are SPDT (ie. output power switches over between pins 87 and 87a). I have some spare Lucas and Bosch relays of both types, and want to swap in a known good relay as I continue debugging my "intermittent" cruise control...

Also, if someone has info on the above, how about a bit more??? If one or both the relays are the On/Off type, are they normally "open" or "closed"??? Thanks for any help!
 
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dhuddleson

Well-known member
Apr 21, 2004
128
0
Ottawa, Ontario, Canada
Cruise - relay is fine. Cruise ECU???

This weekend I traced out the location of the Cruise lockout relay on the Disco I. It is behind the RHS (passenger) side kick panel. This is a GREEN relay, and is normally CLOSED (allows power) when the dash cruise switch is on, and the vehicle is in DRIVE. Using a volt/ameter, I checked it was working correctly when CLOSED and when OPEN. It checks out OK.

The vacuum pump tests OK with 12V applied. The vacuum hoses are good, and vacuum holds when applied manually (by mouth - ugh!) Vacuum break on brake pedal adjusted correctly.

So what is left??? I think only broken wiring (unlikely) or the Cruise ECU (behind glovebox). Has anyone ever had the ECU swapped??? Can it be tested?? Is there a test procedure I can follow with simple tools like a 12V source (battery) and a volt/ameter?

Thanks for any help,

David
 
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kitscott

Member
Oct 3, 2004
15
0
Reply to both David and Joe

David, I don't know if you've come across this yet or not, but here is my cruise control electrical troubleshooting guide. It should at least help you rule out electrical problems between the ECU and various buttons and the vacuum pump.

Joe, did you get your ECU switched out? If so, are you still having issues??? How different is your model year from the 98? What I mean is, how possible was it to follow the troubleshooting guide? I'd like to have some idea how applicable the guide is to other model years and you could provide me some good info. Thanks.

Good luck and HTH,

Kit
 
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