Cruise control

[daljames]

Hi All,

Having an issue with the cruise control. It occasionally drops out, when it does, i can hear the relays click, and then it doesnt respond again. Sometimes coming back when i press set in half an hour or so. Not any more. Dont seem to have anything.

Ive got a GEMS. Ive checked the auto box XYZ switches and all work ok, the HI/LO range sends the correct signal, the switch registers as on, the brake switches work normally, the vacuum lines are fine i have followed all the procedures in rave for checking those and it opens the throttle easily, the wheel speed signal is only thing to be checked, however no faults on ABS/TC, will check speed signals with a driver when i can rope one in...

Anyone got any ideas/tips??

[Junosi]

Could be cruise control ECU. Brake switch and vacuum lines are the usual suspects - but you've checked them. I had the same symptoms on both my old Discovery and current P38 - the occasionally working thing is the main clue I think - it got progressivly worse until it rarely worked. Replacing the ECU on both vehicles fixed it up. It was part number AMR 1173 for both my vehicles ('98 Disco and '95 P38) - I believe later model P38's use a different part.

ECU is located near the steering wheel in that access panel under the wheel

[adm333]

Have you reset the brake switch ?

You have to remove the main panel under the steering wheel and the black panel that surrounds the pedals.

Reach up the brake pedal until you feel the switch plunger.

push the brake down out of the way and gently pull the plunger out towards the brake you will hear a ratchet clicking sound.

Then slowly release the brake pedal and it will click it to the correct position.

This works for me when I occasionally lose CC as you have described.

For 10 minutes effort it can't hurt to try.

Dave

[daljames]

Thanks Fellas, was afraid of the ECU bit... Anyway, LR stealer said its NLA, No Longer Available. Anyone ever contacted a UK dealer for parts and if so any recommendations? Also any wreckers to ask?

[Grumbles]

Perhaps try some of the local independent Landrover Spare Parts suppliers for your ECU. Or get a second hand unit - some suppliers will back their used parts with a 3 month replacement warranty.

[Junosi]

ebay.co.uk is your friend - search for 'p38 cruise ecu' or similar

[DT-P38]

Agree withy Junosi on the ebay.co.uk they have it all and super cheap compared to here... you just need to wait and pay a little extra for freighting from UK. I have used Island4X34 and P38spares and both are good to deal with and reasonably competitive for freight and time. Also try Andrew E on this forum as he wrecks a few P38's and may have parts sitting here ready to express post to you.

[daljames]

Ok update.

Gone through the ETM in RAVE again. Seems i have no signal from the BECM to terminal 11 on Cruise ECU. Asks for 5 volts with ignition at stage II and 2.5 Volts ignition at stage II and wheel spinning. Cant even get the 5 Volts without wheels spinning. Not a broken wire as i have this YR (Yellow red) wire back to the BECM and tested. Hmmm, anyone good with BECMs? I have hooked up my Faultmate to see if speed signals are going around and there are signals from all 4 ABS sensors, from the gearbox sensors and from the GEMS. Where to now??

[BusinessConnected]

I had problems with non-functioning Cruise Control in one of our 2 x Pre 99 HSE Range Rovers... did all the normal troubleshooting to no avail. Purchased a Good Used Cruise Control ECU (AMR1173) and resolved all issues.

Very quick and easy to change over, was only 20 Pounds Inc Shipping from the UK for a good used one.

Theres 3 or 4 on Ebay UK/USA at the moment.

[andrew e]

Have you reset the brake switch ?

You have to remove the main panel under the steering wheel and the black panel that surrounds the pedals.

Reach up the brake pedal until you feel the switch plunger.

push the brake down out of the way and gently pull the plunger out towards the brake you will hear a ratchet clicking sound.

Then slowly release the brake pedal and it will click it to the correct position.

This works for me when I occasionally lose CC as you have described.

For 10 minutes effort it can't hurt to try.

Dave

thanks, i have trouble explaining this to people in words and you have summend it all up nicely.

Oh and dallas, check your vac lines too. all of them.


Andy

[Range Rover Rogue]

Just on the subject of non functioning Cruise Control, could somebody tell me if you turn on the CC switch on the upper console & the orange light illuminates, do any other lights appear within the dash near the speedo telling you if the CC is working mode or or not. I've checked fuses, all vacuum hoses but still no luck. But I would hate to buy a ECU until I'm 100% certain that its gone.

Ange

[Scouse]

No, there's just the light on the switch itself.

[Junosi]

If you know anyone else with a similar year P38 nearby you could borrow their ecu for a test drive to prove whether yours is at fault or not. They're very easy to get at and replace/swap (on my '95 it is anyways)

[daljames]

OK, update. I bought a used Cruise ECU and inverter from EBAY UK and installed it went for a run and.... no luck. Still no clicking relays and my initial diag using the ETM in RAVE appears unchanged. I am not getting a speed signal from the BECM to the cruise ECU. (Which results in the flowchart pointing to the BECM or the wire from BECM to Cruise ECU, checked wire, not broken). I am aware the BECM is getting a signal from the ABS ECU, checked this with meter. I am also aware using faultmate that all the other ECU's that have a speed input are receiving their signal from the BECM. Anyone know of anywhere in Sydney that are any good with BECM's?? Or should i just delve in and have a go myself?

[andrew e]

Give lee at LAB electronics a call 02 48711218, hes in mittagong and reprograms BECMs while he sleeps. (well sort of....) He is a retired ex landrover mechanic who is in love with the P38 becm.

If He cant help you, and you feel adventurous, I have a cracked spare BECM you could try.

Andy

[daljames]

Ok latest... Took it to Lee as per Andy E's advice, thank you Andy. (Id like to know half of what i imagine Lee has forgotten about P38s...)

As per all the tests in the ETM i had previously carried out, the only one it failed with Lee was also speed signal from BECM to cruise ECU. He'd never seen it before either. So looks like a second hand BECM required.

One thing I am talking to Lee about is if we can piggy back a speed signal heading to another ECU say, EAS, GEMS or HEVAC. If anyone knows anything all ideas welcome....

[daljames]

Ok so update...

Well, i thought I would check my battery leads with the ETM test and it failed dismally. A 1.3 volt drop from Alternator to battery so i replaced my battery leads to the earth points and the alternator and sanded the earth points in the engine bay. ALso replaced the alternator to positive battery lead. All voltages MUCH better after a run. Thought id just give the cruise a try, dunno why i bothered but..... jackpot. Its working again! You bloody beauty! So obviously, the voltage output from the BECM for the cruise ECU requires a healthy 12v for the ABS ecu and BECM to send it with enough err, balls, for the cruise to pick it up. Oh and gee it starts quick now!

So thanks to all for suggestions. Goes to show the importance of those earth points and battery leads many threads talk about. Thanks to Andy E for putting me in touch with Lee too. Top blokes both!

If you ever need a second speed signal output, you can use c255 pin 10 (HEVAC speed signal) as well as pin 20...

[glenhendry]

Great followup, thanks for articulating your fix. Good on you for sorting it out. This will be valuable to many in the future I imagine.

[daljames]

Another update....

After getting good performance for a while it fell back into the old patterns. I have piggy backed pin 10 connector C255 (yellow wire HEVAC speed signal) with pin 20 connector c255 (yellow wire red stripe cruise speed signal) and all good and settled. So far......