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1995-2002 Range Rover P38A
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Discussion Starter #1
Hi,

I'm having problems with my Dashboard when it rains. I'm after confirmation I should be looking at a new BECM?

Dashboard completely off including speedo. Only item that works is the SRS Light

It can also have the following errors. Dashboard won't go to sleep and continues to show Air bag fault.
Indicators, Rev counter and Speedo works.
However Airbag fault, Fuel Fault, Temperature fault and Electrical fault all show.


New Fusebox, and alternator.
Earth checked in footwell, and below battery box.
Floors are dry...But it happens with its been raining.
Clears if you drive and warm up the car for between 15-120 minutes

Im not electrically minded and it's doing my head in not knowing how much fuel is left.

I have seen a lot of posts saying its the BECM, but no one confirming this fixed the fault.

Has anyone seen this problem before and successfully fixed it?

Thanks

Barry
 

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I've seen dead dashboard with just SRS showing before. All it needed was a squirt of contact cleaner in the RH plug to the instruments. A BeCM fault will be there all the time, not come and go, it's a dodgy connection.
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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I have seen a completely dead dash be a few things - BECM problem being one of them, but also, in my opinion, one of the lesser likely causes if there doesn't seem to be any other electrical issues.

The dash is fed from Fuse F1 in the BECM fuse box (though unlikely to be that if it works some of the time).
I would do as Richard_G suggests and clean the connector at the instrument cluster, and also there is a ground point behind the kick panel in the RH Front Footwell (where the bonnet pull is). It's known for getting moisture in there and there are connectors that can go green and horrible, and the ground point can corrode too.

If it is traced to being a BECM issue, then I have the diagnostics and a bench test setup that I can check it all out and see if I can replicate the issue. But chances are it's a bad connection or break in a wire in the loom between the dash and the BECM.
 
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1995-2002 Range Rover P38A
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Discussion Starter #4
Hi, Could this be a battery issue as it seems to happen over the winter and when its damp?

My battery is a Bosch S4 with 70Ah and 630 CCA, so is on the small side for a 4.6 Gems. Has anyone seen similar with the dash? What faults do smaller batteries normally cause?

My car always starts regardless of weather, so don't want to replace unless there is a good chance it will fix it.

Thanks in advance.

Barry
 

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Size of the battery isn't really that important as long as it is fully charged and gives sufficient current to start the engine. Usual symptoms of a less than perfect battery are Gearbox Fault, ABS Fault, Traction Failure, EAS Fault, etc coming up on the dash.
 

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1995-2002 Range Rover P38A
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22 Posts
Discussion Starter #6 (Edited)
Hi,

Im suspecting the above is caused by either an Earth or battery fault. Can you look over the following please and see if anything jumps out. Is the battery FUBAR?

1. Engine off, all accessories on for 30 seconds, then off. What voltage 11.6
2. Voltage across battery at idle (no electrical load) 14.2
3. Voltage across battery at 2000rpm (no electrical load) 14.25
4. Voltage across battery at 2000rpm (everything electrical switched on) 13.8
5. Voltage at ALTERNATOR at 2000rpm (everything switched on) 14.43
6. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm - 110mv (millivolts please)
7. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load 0.50v
8. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle 0.10v
9. Check voltage drop from 1st ground point to block 0.10v
10. Check voltage drop from Alternator Housing to block 0.12v
11
. Voltage from alternator positive to alternator housing 14.26

Its the first time in over 30 years I have touched a multimeter. Do the results look okay?




Thanks

Barry
 

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1995-2002 Range Rover P38A
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22 Posts
Discussion Starter #8
Sorry to be a pain.

Whats your thoughts on this one with 750CCA?

Reason is this comes with a 4 year warranty and is £25 cheaper. Its jumping by 120CCA and 30ah over what I have now and I don't have issues starting.

I have emailed them to see if they will have the 1000CCA in stock soon, but the above was my plan B
 

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I normally get them from battery megastore but they are showing the MF31-1000 as out of stock at the moment. I've bought 5 over the years, two for my cars and three for others but I can't see why the 750 won't be up to the job, as you say, it's more powerful than what was fitted originally and isn't quite so big. The 1000 is the biggest you can get that will still fit in the space.
 
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1995-2002 Range Rover P38A
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Discussion Starter #10
I missed the cheaper battery as tried charging my battery this morning to see if it made a dfferences. With all the electrics I could stick on, it dropped down to 11.15v

I'm hoping this cures my electrical issues in damp and cold weather
 

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That's definitely fubar'd.
 
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LEGACY VENDOR
1995-2002 Range Rover P38A
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I had a MF31-750 in mine for 4 years, and now have a MF31-1000. The 750 is up to the job, and was physically about the same size as the -1000. 750CCA is enough to turn the engine over no problem.

The biggest thing with the P38 batteries is a AH (Amp-Hour) rating, as that is more the capacity for running the electrical side of things (simply put - there is more to it than that) - but anything over 100AH on a P38 is good.. 70AH is low given the amount of electrical systems and the currents they can draw!

If you've gone for the -1000 then it should keep you going for a good few years. My last one again lasted well over 4 years.
 

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1995-2002 Range Rover P38A
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Discussion Starter #16
Fitted new battery today and the car starts much quicker. Even the windows and sunroof work much quicker..

Now to wait for the cold weather to see if its cured or not...
.
 

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1995-2002 Range Rover P38A
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Discussion Starter #17
FFS

Well its rained last night and my dashboard is off again this morning.

Anyone any more ideas or suggestions before I cry.

Local car sparkie is £100 an hour, but hasn't touched a P38. Im now spending money I don't really have
 

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1995-2002 Range Rover P38A
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Where in the UK are you?
 
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