Can't engage low range (P38a)

Hi Folks,
Swapped my wheels around today. Tried to engage low box as per instructions and I kept getting "select neutral" on the message screen ..... the thing is I was in neutral. Any ideas please?

lenb

is it auto or manual,tiga

Hi tiga,

I've been out so only just got your question, but in answer: my RR is a manual.

lenb

Hi ya thats good as the system is slightly easier to work with than an auto,on the side of the gearbox is a switch that lets the TCU,TRANSFER BOX ECU,know that you are in neutral so i would start and check this first and the wiring to it,the other thing you can try is put fuse into see if the transfer box will select neutral in the transferbox,i would do this first then you can see if the system works the fuse no is either 11 or 13 but i know its the top line of fuses under the drivers seat, put a 5 amp fuse in the top right hand last slot,you should hear a clunk and message on display should say transferbox neutral, although this message is generated as soon as you put fuse in by the becm,when it says neutral on dash just try putting in gear and pulling away,you should have no drive,but it may come up and say select neutral again,let me know off outcome and i will relay more details,tiga oh yes what year is it as the wiring diagrams are different

Hi tiga,
Just tried the fuse and sure enough it would not move. It did not come up with select neutral again but did say transfer neutral & high. The RR is Jan 1995, one of the first. It's done nearly 94k and has been well looked after. The only other suspect thing at present are the air suspension bags that are perishing.

lenb

well as long as it went into transfer box neutral,and had no drive im sure its either the neutral switch on the side of the gearbox or wiring to will have a look so i can give you more info,will get back to you tommorow good luck tiga.

Ok thanks, I will have a look round tomorrow morning.

lenb

Well I had a good look around this morning, pulling off connectors and putting them back on again (except one in engine bay that I didn't want to risk breaking), assuming of course I was looking at the right components (which I won't know until my Brooklands workshop manual arrives next week). Needless to say I still have the same problem :-(

lenb

hi lenb not forgot you been busy, right here goes the rave disc i have says that depends on year you could have a switch on left hand side of gearbox or a switch on the clutch, if its located on the clutch pedal box area that will be easy to find just the lower panel,if its located on the gearbox it will be on the left hand side of the gearbox passenger side,there are 2 switches buy the looks of it side by side 1 is reverse gear switch the other is neutral switch,picture not to clear which 1 is which,first of all make sure reverse gear lights come on very important so tcu can detect not in a gear,the connectors look the same pull off a connector and armed with a paper clip earth toegether both pins then look to see if reverse lights are on,ignition on of course if no lights come on refit connector, try other connector and you should now know what connector is what,the wire only needs to be earthed out to send a signal back to the tcu to say its in neutral then try low range if this works get yourself a new switch or feel free to use paper clip when low range needed HA HA!an easier way for me is remove passenger seat trim and pull out tcu and earth pin 34 out which is a brown wire,i hope this helps if not call the samaritans no only joking will help if i can all the best tiga.

Hi Tiga,

Thanks for the info, I will let you know how I get on but it may not be today as I've put my back out and am struggling a bit (mind you laying on a hard surface is supposed to help!).

Cheers

lenb