P38 Incorrect 4th Gear Ratio

Evening

I am hoping someone can help point me in the right direction for the latest of my many p38 faults!
Car was running ok until new years eve when i blew a fuse on the engine management system. I had the AA out and they changed the fuse but said they wouldnt be able to trace the fault at the roadside. During the evening I blew 4 more fuses trying to get home until eventually i ended up on the side of the road for 4 hours waiting for a tow truck!
My battery died during the wait but i had an auto electrician out a day or so later and he found a small length of wire that had become exposed that was shorting in the engine bay.
I had that replaced and all seemed ok but since then the auto dip mirrors dip but dont go back to normal, the suspension seems to take a lot longer to switch between the ride heights and most annoyingly the 4th gear seems to be limited at just over 2000 revs.
I have hooked it up to a code reader and get the P0734 Incorrect Gear Ratio in 4th Gear error.
I thought it may be related to a bad earth connection, i checked the one to the alternator and it seemed ok, i did get an alternator message if i left the ingnition on ii so checked the charging voltage which was pretty much nothing. I have changed the alternator and the message has now gone but i still have the other issues.
I did have a leaking transmission repaired recently and to me the fluid seems a little high but i am not sure

Does anyone have any ideas on what to check next!
Many thanks
Carl

Petrol or diesel? Which fuse blew? Gearbox messages can be due to low battery volts.

It is a 4.6 petrol with LPG fitted
I think it was fuse 23 it is part of the EMS circuit before relay 19 if i recall the AA guy correctly
the battery tests fine and i have just fitted the new alternator so i think all is ok, it could be an earth though

I dont mind the messages but the gears are not right when driving it, they seem limited at about 2100 revs and the gears seem to hunt when they shouldnt do, i lose most power when going uphill

i hope you have some ideas!!

Battery tests fine? Did you test it yourself? What voltage do you have with the engine running? Should be around 14.5v after a short time with the engine running. Should be around 12.8v after a short time after stopping the engine. Low volts = problems. Check the cables from the battery, they have been known to rot away inside the plastic. Check the underbonnet fuse box and relays for signs and smells of burning.
I would have to look up fuse 23.

Thanks for the help
Some updates are that i have double checked and it was in fact fuse 26 blowing not 23 as i originally thought
also i have added an earth from the battery to the bodywork as i read elsewhere that that would help rule earthing issues out
i have replaced the MAF with a new one although not OEM, and the air filter and pollen filters (not connected i know)

All have made it a bit better but still lacks power and gears still seem sluggish to change
twice when starting the car i got approximately 6 - 7 beeps yet no messages appeared on the message centre although the handbook suggested one should have done

what would you guys try next?

thanks

You need to get the gearbox ecu checked while driving and have the gear position switch checked as it could be faulty
Also check the plugs at the rear of the pass side head as they fill with oil causing problems too

Now that you have sorted out a lot of the problems,
you need to clear the faults with a rovacom, autologic or similar
and then see if any of them come back.

As Datatek says, gearbox errors come about because of low volts in the system.

This can affect the engine ecu and may have put some of the settings
into 'limp home mode'

You can use the same diagnostic kit to put the engine into 'learn'
mode (aka 'reset all adaptions') as the changes you have made with the MAF etc will take a long
time for the ecu to compensate otherwise.

While you are doing this, check the airflow through the MAF, it should be around 20 - 25
if it is about 17 you may have a dodgy MAF, cheap chinese ones don't last long.

I am presuming the P38 is pre 2000, as he post 2000 don't tend to have MAF problems as often.
BTW, why did you change the MAF?

Mike .

thanks for the help
it is a 1996 p38, i changed the MAF as the general feedback i got for gear ratio and other gear box errors was the maf, i had already changed mine once and so thought it was a likely cause as i had bought a fairly cheap ebay one!
i guess i will have to book it in somewhere and bit the bullet on the tests mentioned.
thanks again

CarlJackson said:

thanks for the help
it is a 1996 p38,

i guess i will have to book it in somewhere and bit the bullet on the tests mentioned.
thanks again

Click to expand...

If you shop around, you can get proper diagnostic kit plugged in for a reasonable price.

Go to an Independent Land Rover specialist who can use a rovercom, autologic or T4 system.

There is a specialist in Liverpool who will do diagnostics for £25 a session.

Most others should charge around £30 - 40 for it.

I don't know where you are based, so I am only telling you my local prices to give you an idea. Main dealers charge £80 - 100 these days I believe, so it is worth shopping around.

Mike .

i am in west sussex, i have had chichester landrover suggested so i will try them, main dealers wont even plug it in as it is lpg converted!