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Premium Member
1970-1995 Range Rover Classic
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425 Posts
It has been ages since I last logged in, had forgotten my password .. and the forum was linked to an old email.

Here is the issue..
thank you for your support.
I am currently struggling with a p38. The air supension has been removed so this is no issue

Last week 'some' garage connected a `scanner' to no avail. Before the diagnostic seems to have worked, but it wasn't me.

Since, we received the car with a fine collection of electrical 'repairs' which I have to sort now.

There is now no way I can get either Hawkeye pro, its little brother or the Blackbox Faulmate MSW to work. All work perfectly on every other Landrover which we have i the garage with diagnostic plug and a battery connected. (which excludes my Rangie of course)

it doesn't even light up. I tried the BB with an external powers supply because I had a P38 among my clients in france with a dodgy supply line.. nothing it starts up but does not connect

here is what I got

pin 1 12v
4 and 5.., good tested earth
7 10.5V at rest or ignition stage 2, 14V when started (checked with voltmeter and oscilloscope, 14 V flat out)

11 and 12 some undefined low voltage sinus.. but not really important.

14 11V at rest 12.8 with engine running
15 9V at rest 10V with engine running
16 12V with ignition on 14 with engine running

A friend who kindly measured the pins of a NAS spec p38 in his garage tells me he has ZERO V on pin 7, the rest is identical.

I have also measured the pins on C102 and get the same results.

Any ideas welcome.. I feel pretty lost.yes fuse 33 is good and has 12V.

and yes I have removed corrosion from those plugs.. but no real problems. I disconnected EAS and airbag ECUs, even the engine one.. Still nothing
 

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Registered
1995-2002 Range Rover P38A
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1,420 Posts
Remove the sill plate on the RT side and carefully inspect all the wiring. There is a lot of it in there and you will need to un tape the bundles to do this properly.
I had an issue with my 02 which was caused by the wiring loom having been obviously slammed in the door at the factory prior to the rubber seals being installed.
as a result, the insulation on a dozen wires was cut in 2 places. The factory guys simply taped the damaged insulation and shoved the bundle back under the sill. A few years, and some moisture, and the wires had corroded through.
The kicker was that when measured for voltage, you would actually see odd voltage readings present as it was being conducted by the copper oxide in the broken cables.
Certainly worth a look.
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #3
thanks a lot Bolt.
I will take this string out tomorrow, i had already opened it because it seemed a bit moist. (Our climate is moister than Port Douglas in the rainy season :) )
In the meantime I took out the Hevac today because there was an odd mothydication in the wiring and I guessed it could be the issue. Well at least the Hevac doesn't go dim any more when you press the brake pedal,:razz:. Something my apprentice noticed as well as an odd wire in the cigar lighter.
So far no ECU was the problem nor the most suspicious connectors.

Hence your idea is certainly the next step.. I will let you know the result.

In case anyone feels like measuring the voltage on his or her diagnostic pins I would really appreciate.

greetings from windy Tilarán to QLD.
 

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Registered
1995-2002 Range Rover P38A
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1,420 Posts
Aloha,
You did not mention the year of the RR, but there was an modified HVAC set up which added an external relay on earlier years....I ~think ~ pre '98 That could be what you are seeing.
As for the dimming, be sure the mod, if that is what it turns out to be, was done per RR instructions, and while you are in there, check all connections to B+ and all earths behind HVAC. Loose wire on either could cause dimming issues......especially a bad earth.
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #5
Interesting...but...
You would never guess what they did..
The auto knob is dead and loose so they cut that line and a few others to fiddle in an external switch next to the cigar lighter. and they also fiddled an earth to help the radio :oops:

The car is early 97, diesel manual originally sold to Italy.

it is actually in excellent condition apart from the injector nº4 and the wiring.
 

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Registered
1995-2002 Range Rover P38A
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760 Posts
As bolt says, definitely an earth problem somewhere, I’d be tempted to check all the wiring blocks in the footwells, both sides. There a known problem with many faults, including the obd socket, just cut, solder and heat shield them, that way you know your getting all the right signals, clean all earths well..
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #7
NO earth is fine as I wrote in the beginning.

Have pulled out all the sill cables in the morning .. nothing visible. Right now finished to pull half the dash out. Water ingress from pollen filters...
Will keep you posted.
 

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Registered
1995-2002 Range Rover P38A
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1,420 Posts
As Chris10 mentioned, and you have now confirmed with the bit about the water leak. Pull off the Left and Right footwell kick panels and inspect / clean/ and or chop out and replace the corroded plugs as necessary.
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,159 Posts
You should have 12V on pin 16 with the ignition off aswell - it's the feed for the diagnostics socket from the underbonnet fuse box, and should be a permanent live.

There are diagnostic wires that run through the kick panel in the RH Front footwell. (and also the power from the fusebox to the OBD socket comes through there).

The other place that is worth checking is in the fascia loom - as I know on RHD vehicles (I presume similar for LHD) have a splice in that loom for the 2 main diagnostic wires (Pink/Red and Light Green/Red) - which I've seen a few times now and causes problems with connectivity to a number of the ECU's.

I'm not at home for another few weeks, so I can't measure what the voltages are on the other pins - but pins 7 and 15 are the Pink/Red and Light Green/Red diagnostic wires.

If you have even a slightly dodgy connection (high resistance etc) on the Black/Purple wire (pin 5 that goes to ground, but in the engine bay) then that will also cause connection issues to most ECU's I've found - it seems to be the data ground, rather than the unit ground that the solid wire is. This Black/Purple wire also goes through the kick panel connector in the RHF footwell that get corroded.. I definitely think it's worth a very close look - and any sign of green corrosion, then cut the connector out and solder/heatshrink all the wires together.

If your friend got 0V on pin 7, then it could be corrosion somewhere in the loom splice, or the connectors) which is giving it a bad voltage reading.

Have you tried the reading on that pin with the BECM connector unplugged aswell, to see if it isn't a weird BECM issue which is holding that wire high at 12-14V and not pulling it to ground?
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #10 (Edited)
update

Thank you Bolt, Marty and Chris, Here is an update HOPE somebody has patience with me.. checked all earths again, but nothing wrong. Get about 50 Ohm between engine ECU and the round connector under the expansion tank but nothing else that look suspicious. found lots of bad cables behind the HEVAC. (this one is more like havoc ) Found more green and tape gunge in the driver door sill. Got rid of it and spent a lot of time with fine contact brush and cleaner. disconnected air suspension ECU, relay etc. Hevac problems eliminated. Was left ONLY with engine and BECM connected. Stilll the same 4 /5 ground, good. 16 - 12V or 13.5 depending on ignition switch. 7 is 10.5 WITH engine ECU connected, 12V without. 15 is 7 ish with engine ecu connected. all the ABS and other stuff was disconnected. the connector C204 on the LHS was also treated .. but makes no difference whatsoever. For my own peace of mind I connected my Hawkeye again to the Disco td5, a Puma Defender and a Td5 and all is fine. Voltages are never 12 on 7. Even a (sorry about the bad languange) Hyundai had to undergo my test. What am I missing?? I have taken the BECM out now, surprised to find a H version.. car has no electric seats or any fancy stuff. Before I through in another BECM which is a least popular solution with me since I can't read the old one do you have any ideas? One WEIRD thing.. if I switch the ignition on AND connect the Hawkeye voltage on 7 drops to 0 afterwards. As if some condenser was holding the offending 12 V.
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #11
Ho Marty, I took you advice very serious and did triple check the earth. Only noticable resistance is between engine ecu and round plug under the expansion tank.But alas, it makes no difference if I unplug it, the voltage goes up to 12V. With the BECM out there is no reading whatsoever.
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,159 Posts
hmm.. that's a strange one...

If the BECM is disconnected from the diagnostics wires, then can you read any other ECU's? That would in theory rule in/out it being a BECM problem at least...
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #13
Arrrgh the bad Internet dumped my reply twice.
The plug with the diagnostic line to the becm feeds also some other important function such as ignition switch.
Hence I am not surprised that it doesn't work either without the becm.
Today I will see to another p38 in Libéria. .gotta get going soon. This one has most likely GEMS trouble so maybe I can do an experiment and disconnect the plug.
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,159 Posts
That's weird - as there is a mention, I think in Nanocom manuals that if you have an unlocked BECM then it can sometimes affect communicating with the HEVAC. And if that is the case to disconnect the plug with the BECM diagnostic wires in it.

The diagnostic wires to the BECM go into C255,
Ignition Pos I feeds in on C256
Ignition Pos II feeds in on C257
Ignition Pos III feeds in on C258

So there should be no interruption in ignition functions if you disconnect C255 to stop the BECM from being connected to the diagnostic wires.

Unless something else is messed up in the wiring of course - which given that you've said there are other wiring issues in the dash, who knows...
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #15 (Edited)
OK. There is light at the end of the tunnel... Thanks to all who helped.



Special thanks to Marty as his last post pointed me the right way.

It wasn't the ignition feed but the key in feed... in C255.


One well... not really short but a 50K Ohm connection behind C255 in the BECM,

And another one inside the fusebox, also 7.5 KOhm in the fusebox.

All caused by the Havoc in the Hevac wiring.


The other clue was everything going very dim when you pressed the clutch pedal, which actuates a switch that also is fed through C255.


So... fuse box on order, it had already been botched up. BECM soldering on my plan for today.


Hope Marty reads this and sees my PM that I sent about a Hevac yesterday, I might need 2 of them.


I haven't done 3 P38s since I am here and now I get 3 in a row, all quite interesting.
_BBB4711.jpg
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,159 Posts
Glad you are on the right track now - that's a lot of wiring to sort out!

I was travelling back to the UK yesterday, and am heading off again tomorrow for the next job, but will check my PM's now.

Let us know when it is all back up and running!

Marty
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #17
Update.. fixed a lot of things.. BUT it won't start and I can't talk to the BECM. I can talk to everything else as in ABS, Diesel ECU, even the suspension that is not present any more. Already tried another BECM. Tried earth.. good. 12V to BECM - good - C255 to diagnostic plug shows no resistance problem. What the Heck am I doing? thanks for any hints..
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,159 Posts
So no talking to either BECM? That is weird...

Do you have the ignition on when trying to connect to BECM? If so, try it with ignition off - BECM responds best with ignition off.

Otherwise sounds strange... checked the splice in the fascia loom where the 2 main diagnostic wires splice from the OBD socket off to their various ECU's?
 

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Premium Member
1970-1995 Range Rover Classic
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425 Posts
Discussion Starter #19
Thank you Marty,
it gets even weirder. it also doesn't accept the EKA.
It will tell me 'motor desconectado' which I translate to engine disconnected, in the French ones this came up as disabled.
Then it tells me to press the fob button... OK I do, it DOES unlock the doors.
But when I do the EKA it won't work.

So I did Marty's patented door latch test ®. All fine on the driver's side.

I feel like a right idiot. yesterday I started a P38 which had been dumped for 3 years and 7 months as a non starter, cleaned the green death out of the usual connectors, did EKA 3 times and at last Vrouuum off it went.

What the heck am I missing..
 
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