P38 Cruise control

[deano2469]

hi all, I'm having a drama with my cruise control. Over the years I have had problems with the hoses splitting and it failing because of that. This time I had exactly the same symptoms yet I can't find anything wrong with any of the hoses. the switch lights up and I can hear a click when I press the button on the steering wheel. Is there a way I can find out what else could be wrong?. I know there are a few switches and relays but where should I start.

Thanks in advance.

Deano

[TheTree]

Hi

I notice mtb_gary in his magazine article said he spliced in a later model more reliable Cruise Control unit

Mine is not working either :(

If you take the drivers kick panel off and get to the end of the vacuum hose, in the absence of a vacuum pump you can suck on it while someone else watches the cruise control bellows. MNine passes this test but that is as far as I have gone so far.

The brake pedal switch is a candidate for failure as well, not sure how to test it though

Steve

[mtb_gary]

Hi

I notice mtb_gary in his magazine article said he spliced in a later model more reliable Cruise Control unit

Mine is not working either :(

If you take the drivers kick panel off and get to the end of the vacuum hose, in the absence of a vacuum pump you can suck on it while someone else watches the cruise control bellows. MNine passes this test but that is as far as I have gone so far.

The brake pedal switch is a candidate for failure as well, not sure how to test it though

Steve

Steve, the brake pedal test is straight forward. When you turn on the ignition do the brake lights stay on? If they do the switch needs resetting.

PS it was Simon that did the creative part with the cruise control ;)

Gary

[p38driver]

There are two brake pedal switches one for the cruise control and the other for the brake lights . The brake switch for the cruice control has a vacuum hose connected to it as well as a electrcal plug . I have the same problem with the cruise control not working just finished going through the long winded rave procedure. Everything checks out ok but still no cruise control so i am now going to try the ecu mod.

[blindin]

I found that even though the hoses look good, they tend to leak at the fitting. I suppose it is just the hose getting worn. If you can here clicking, the ecu should be working, and that would get me looking at the hoses. It could also be the pump, but I've never had any thing to do with them, always been the hoses, and the ecu which was changed. For $15 of hose, I would start with that, especially as you can hear the clicking. You could always block of the hose to the brake switch just to check that isn't the problem.

[p38driver]

There are two brake pedal switches one for the cruise control and the other for the brake lights . The brake switch for the cruice control has a vacuum hose connected to it as well as a electrcal plug . I have the same problem with the cruise control not working just finished going through the long winded rave procedure. Everything checks out ok but still no cruise control so i am now going to try the ecu mod.

I now have my cruise control working after fitting a D2 unit

[p38driver]

.........
You just need a bit of patience soldering all the wires and checking to make sure you have got them on the right pins . I made a patch cable instead of splicing into the original wiring

[TheTree]

Looks like I may need this mod as well, once I get the beast running nicely again that is!

Steve

[TheTree]

You just need a bit of patience soldering all the wires and checking to make sure you have got them on the right pins . I made a patch cable instead of splicing into the original wiring

Hi Mate

Any chance of some details on the cable?

It seems a few of us here need to do this mod

Steve

[TheTree]

If I can get hold of the connectors I could knock up a couple of leads

.did you salvage one of the connectors from the old ECU or did you manage to source one?

Steve

[p38driver]

......

Yep thats the instructions i followed thanks for the info.

[TheTree]

Having read the instructions correctly now :angel:, I think I know where I can get an older ECU to salvage so I can make the cable before I pull mine out.

Steve

[Limespider1963]

Does anyone know where I can have my BeCM Controller tested. I went to a British Car Mechanic in Brisbane replaced ecu, brake switches, Vacuum hoses, Cruise Control Relay. I have been told the number 1 pin on the BeCM controls the Pump supply for the Cruise Control to work.

Does anyone know if a second hand BeCM would plug straight in without other links being required to be programed.

I live near Moree NSW. Does anyone know where I may be able to have a professional look at the BeCM in Newcastle or Sydney.

This is for a 1996 P38A

[prelude]

The BeCM is a pretty advanced and complex system, for it's time. (pre CAN)

It communicates with just about everything in the car including the dashboard and the ECU. iirc the serial number of the key, BeCM and ECU need to be the same else the car won't start. Also, the BeCM and the dash both register the ODOmeter. The one with the highest number wins so that means that if your donor BeCM has a high mileage, it will overwrite the dash and all of a sudden you have a high mileage car :)

So, no. Swapping out BeCM's is not recommended.

-P

[Scouse]

There's Labtronx in Mittagong who does work on BECMs.
Has your mechanic followed the comprehensive diagnostic procedure in the ETM?
A quick look through finds 2 CC pump tests and neither involve the BECM.