P38A Cruise control

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J L Carr

Active Member
Posts
360
Location
Hemel Hempsted
Hi Guys, been looking through the RAVE but cannot find any information on the switch that's above the accelerator pedal I have the information for the 1 that's above the brake pedal but not the other one, as I think this must be broken as if I try my cruise control the pedal does not drop. Everything has been checked and the brake switch replaced for new, now there is only that 1 left to change, so help please and Thanks.
 
Don't think the accelerator moves at all with cruise engaged? There are 2 cables on the throttle body - one for the pedal and one for cruise.
 
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Never taken the cables off as it just stopped working and the last time it did that it was a split hose,but this time hose ok so gone through the usual and replaced all but thar switch that I've just found out is the brake pedal switch that's on the accelerator, but it's been like this since I got the car 14 years ago. The vacuum pump is working OK when I tested it out the car as well as the switch next to it,but hope to test to see if there's power getting through to that unit.
 
The accelerator pedal only moves down if you hold the set button to cruise faster !! Assuming the cables are adjusted correctly (see RAVE as usual), setting the current speed for cruise should hold the pedal where it already is.

Also, on a petrol car only the brake pedal has the switch. If you still cannot engage cruise, go through all the troubleshooting steps again (you did do them I assume ?).
 
Been through them all, now it's driving me nuts as I doing around 25 miles on a motorway to get to work,but cannot use the cruise control, so first I changed the red relay then the module next to it,then the vacuum hose and then checked out the vacuum pump was working all ok. Then the last thing I changed was the switch on the brake pedal the ERR2622, but still nothing. The only switch I have not changed is on the steering wheel but I cannot find that one,so that may have to be second hand type.
 
Redo the trouble shooting now you've changed bits & pieces.

Main things are the Set switch actually toggles ECU pin, and when you trigger the pump manually, it should pull the cable fully to open the throttle. Do these with ignition on, and engine not running. Speed input is difficult to do without a scope. You could also try a temporary separate Set Switch wired directly to the inverter relay ?

Mine often forgets how to engage. I switch the cruise master off-on, and then it engages. I suspect the ECU gets into a strange mode for some reason.
 
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