Extended OBD II Codes on a P38

[MrOrange]

Today I plugged in my (generic) OBD II code reader to see what code(s) was causing the "test book" icon to appear to appear on my 98 4.0 petrol and aside a spurious P3999 code I got no codes showing - I know I have at least one problem with blend motors so how come it's not showing? The reader connected as CAN ISO and is able to read the P38s realtime data such as rpm, load, temps, o2 etc. Is this a case of I'm simply stuck not seeing any P38 specific codes?

[P100]

I presume you are talking about the HEVAC system and the little book that appears in the bottom right hand corner ?
Correct me if I`m wrong here but a normal OBD code reader will not connect to the hevac system.

You will need a specialist piece of kit to read what is wrong.

Roy

[alchilds69]

Hi, p3999 is not on any obd list I have. It is more than likely a manufacture specific code. And will need a landrover or specific code reader. I use a obd laptop based reader for work and never been able to read older landrovers ( with obd plug) or rovers in general. Im not sure but they may not be obd2 compliant. The book symbol as p100 said means the fault is with the hvac system. Goodluck

[MrOrange]

bks. Need to pay a stealer to read the HEVAC codes then. I'm guessing it's a stuck blend motor and since I've got the o-rings to do when the weather is better I wondered if the stealer will be able to tell me which blend motor is fubared?

[P100]

A good Indy with the correct kit can access your Hevac system and read any faults present.
Be warned though, they normally contain 2 or 3 pages of faults...
The general faults are normally blend flaps, LH or RH blower motors, or compressor ( which normally means lack of pressure in the system).

Hope this helps

Roy

[eliot]

I'm just going through all this with my P38. If the blend motors are not moving or jamming it will throw the testbook icon. As others have said, you need proper diags - not simple obd2 readers. I bought myself a blackbox faultmate for this purpose.

Whats interesting, is that if the underlying fault is cleared then the testbook symbol will go away on its own (although the fault will be stored in the log) - so if the blend motors are jammed, then you need to fix them. As I have found out - its not just a case of fitting a new blend motor - my blower assembly has stiff flaps, which was causing the blend motor to move very slowly and stall most times. So i've actually removed the whole unit and freed up all the flaps. Not put it back in yet - but I think it will be ok now.

Link to my thread about it:
http://www.pistonheads.com/gassing/topic.asp?h=0&a... in the P38 fold