p38 gearbox fault message 2.5 auto

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p38 gearbox fault message 2.5 auto

Postby james4287 » Fri 05 Nov 2010 2:57 pm

ok, driving last nite cruise control set to about 45mph pressed accelerator and it came up gearbox fault and the injector warning light came on and engine stopped and wouldn.t crank. i waited a few mins and restarted and drove fine again. i.ve checked oil level in box and all ok. oil smells ok and looks ok, not black, burnt smelling etc. i did a quick google search on my phone last night which suggested to me disconnecting battery for a while and cleaning round multiplug under header tank which i.ve done today but not yet tried it. any other views chaps? appologies for grammer i.m on the phone writing this!.
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Re: p38 gearbox fault message 2.5 auto

Postby nisbeam » Fri 05 Nov 2010 5:47 pm

The gearbox message is often caused by low battery voltage. Check it is ok, perhaps the last action switched off cruise and it was the last straw for the battery.
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Re: p38 gearbox fault message 2.5 auto

Postby tabbahenry » Fri 05 Nov 2010 7:39 pm

yep sounds like low voltage prob . had the same prob with mine when it was running . bigger prob at night it happend everytime i did someting with the lights at turned out to be a faulty batt not taking a charge .
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Re: p38 gearbox fault message 2.5 auto

Postby rrp3846 » Fri 05 Nov 2010 8:09 pm

Check the relay in the fusebox (no.15 I think). I had this on mine and after this got warm it would dissconnect
giving similiar symptoms to low battery but also cutting the engine.
Scary whilst driving downhill and loosing powersteering and brakes.
Would restart after a while, but then do the same.
But otherwise go to RR.net and go through their electrical test procedure (sticky under P38)
That will show you if your battery/alternator are dying, also check all earthpoints and battery clamps/
main wiring. It´s amazing how much trouble a bad electrical connection can cause.
Save the planet, drive a V8.
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Re: p38 gearbox fault message 2.5 auto

Postby james4287 » Sun 07 Nov 2010 4:44 pm

thanks for the replies, i.ve swapped relay 15 for one of the a.c relays but theres still a problem as in when at a steady constant speed if you lift off the throttle sharpish the injector light flashes on then off, this has happened three times now once as above when it died totally and came up gearbox fault the other two times revs have dropped but i.ve planted my foot down and its changed a couple of gears and driven on. i left the battery unconnected for ten hours and have cleaned the earths up on the battery, it.s a reasonably new battery but haven.t checked things with multimeter yet. did a quick search which seems possible fuel pump fault with the rotorary pump electronics. any views? i think i.m going to need it plugged in then down the local bosch dealer?
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Re: p38 gearbox fault message 2.5 auto

Postby paul95dse » Tue 10 Jan 2012 12:53 am

Hi, did you solve your gearbox fault issue? I have a similar problem (plus other error messages and my air suspension not working) and suspect it's a ground issue or a short to ground. So far I've replaced the battery, checked the alternator is charging (13.7V), changed the battery leads, cleaned all the engine bay earths and the earths around the BeCM and the footwell earths. Now I can drive the car an only occasionally get the transmission fault code error when driving under low electrical load but at night at reasonable electrical load if I flick on the brights (sorry) I get the gearbox error every time - same if I use the brakes.

Next steps - check the gearbox connectors near the handbrake, recheck the round multi pin connector under the expansion tank. Check the gearbox loom under the car.

This investigation started because my EAS stopped working. I found after some time that the EAS was actually fault free and what was happening was that when the EAS started the compressor to raise the suspension my poor earth issue (assumed) then caused the height sensor voltage (and hence EAS interpreted position) to change due to the electrical load. The incorrect height (too high) would then cause the EAS to switch off the compressor, load then drops, sensors read correctly and pump back on - end result a cycling compressor and weird alternating sensor heights! Anyone had this? But I can't find the cause! HELP!!!
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Re: p38 gearbox fault message 2.5 auto

Postby paintman » Tue 10 Jan 2012 1:11 am

This from the electrical forum for you:
Re: Charging
Postby pistnbroke » Tue 03 Jan 2012 7:07 pm
To be more specific.....First if you charge your battery and let it sit for 24 hrs then if you dont have 12.5v then the batterys is suspect.
Readings at idle and with lights etc on are meaningless ....go for a short drive and then without stopping the engine read the battery volts at about 2000 rpm ./ should settle to 14.4v . If below this then the voltage regulator is faulty.
This does not apply to ECU controlled alternators which need a different technique.
1986 RRC 3.5EFi LPG
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Re: p38 gearbox fault message 2.5 auto

Postby james4287 » Tue 10 Jan 2012 9:29 pm

i changed the battery soon after this thread as it kept going flat, i also cleaned battery connections and haven't had the issue since, or so i thought.

few weeks ago i left the engine idling with headlights/heater/radio all on and had gearbox error again, key'd off and back on and it was fine.

both occasions i've had this error i've had lights/heater/radio on so high electrical load. i suspect poor connection somewhere or the start of alternator fault but until it becomes more regular i'm not spending money on a very intermittant problem, for me anyway!
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Re: p38 gearbox fault message 2.5 auto

Postby rrpeter » Sun 17 Jun 2012 10:51 pm

Has this issue been solved? I have simmilar problem. Sometime when I take gas off it stalls or stops with gearbox fail warning. Sometime when I kick the gas it runs again. It is very worrysome when overtaking someone and all of a sudden the car stops and no powerstearing and abs.
Thanks
Rp
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Re: p38 gearbox fault message 2.5 auto

Postby james4287 » Fri 22 Jun 2012 7:36 pm

Peter, my gearbox fault message hasn't returned since my last post, so again as far as i can guess it's an electrical gremlin, but i have no idea where.

However, if yours is stalling when you let off the gas this maybe a seperate issue, a very common issue (which mine also does) [does your injector warning light flash on sometimes too? mine does!) and is caused as far as i can work out by a fault in the electronics of the fuel pump called the HDK unit. google it. I believe this fault can through up the gearbox error as when the engine stalls the ecu is getting a vehicle speed senser input but rpm signal of 0 and it interprates this as a gearbox error.

With mine, if i drive gently and operate the throttle gently and slowly i can drive thousands of miles without this fault reoccuring. I have also noticed when it sport mode it doesn't do it so often!

hope this is of some help to you..
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