Hi everyone, now I have my 1995 P38 going with a rebuilt motor etc. the speedo has not been working. The scan tool says speed sensor input out of range or something similar. Is there any way of telling which sensor is out of range, or should I just replace them all. I have another vehicle I could pull them from. Also another problem that may be speed related. While I was working on the my P38 I thought I would replace all the air bags, and I rebuilt the compressor and the valve block. And I made up and fitted a manual inflation set of valves. And a isolation switch to cut the earth to the relay under the passenger side seat. So when I got it going the air suspension seemed to work sitting in the yard, up and down. But when I took it for a drive, when I got up a bit of speed it dropped to the bump stops. So now I am driving the vehicle with the EAS turned off as when I turn it on it now drops the drivers side down to the bump stops and pumps the passenger side up to max height. Also I have an odometer error coming up on the message screen. Could all these be related? Also the scan tool has lost communication with the vehicle.
Thanks, Alan

Speedo gets it's input from the ABS ECU so if there is a fault on the ABS system, it can affect the speedo. Do you get an ABS error on the dash? Odometer error will occur if the car has been driven with the instrument cluster disconnected or it has been changed as the mileage is stored in both the instrument cluster and the BeCM and it has detected that they don't match.

EAS should drop to motorway height after 30 seconds at more than 50mph and then size back up after 30 seconds at under 35mph. However, if the EAS ECU is not seeing any speed signal (as well as the speedo) it will also confuse it. Dropping to the bumpstops, accompanied by EAS Fault on the dash and all 4 lights flashing, shows a hard fault but you will need diagnostics connecting to identify the fault and reset it.

Hi Gilbert,
yes it looks like it might all be connected. I will start with the OBD connector. Like you said I can't do much until I have communications. I do have a spare ABS computer, so I could try changeing that..
Thanks, Alan

Hi Folks,
well I have had some success. As the passenger side of the car was in the shade I though I would start there. I removed the glove box and and changer the Wabco computer mounted on the firewall. I cleaned the airbag connector and the connector and the connector to the fresh/recirc motor connector and I also cleaned the OBD plug, and refitted the glovebox and went for a drive. SUCCESS, the speedo works, and the EAS seemed to working also. But I have gained a TC light on the dash. But I have not plugged in the scan tool and cleared all the faults. Not too bad of a result, considering I have both hands bandaged up and right foot and leg bandaged up as well as bandages on my back where I have had skin cancer cut out. Back in tomorrow morning for another operation to remove some more. At least I can drive there in the P38. I might get back to it later in the week when I am feeling a bit better.
Regards, Alan

Have you got the correct ABS ECU? Early cars had the Wabco C system with either no TC or two wheel TC, whereas later ones had the Wabco D with 4 wheel TC. Not sure how interchangeable they are though.

Hi Gilbert, That is a good point, I never checked the part numbers when I changed them over I had a bit on my mind that day. The one I put in was out of a 1998 model , and it seems to be working OK so I think I will leave it alone for now and work on one of the other issues this vehicle has. The climate control unit has a fault saying perment loss of power to the fresh/recirc motors. Do you know where the fresh/ recirc motors get their power from?
Thanks,
Alan

Hi Gilbert,
OK, I found the wiring diagram with the fresh/ recirc motors. It looks like the power comes out of the HEVAC unit and then returns back to the HEVAC unit, and most likely earth switched through a transistor. So it looks like I will be pulling the glove box again so I can see what is going on. Then I will have a chance to check the part numbers on the Wabco computers. But not for a few days, The stitches in my back are giving me hell today.
Thanks,
Alan

A 98 model would have had two wheel TC whereas a 95 could have had 2 wheel TC or may not have had TC at all, so that may be the problem. Is it the recirculate motors or the actual blowers that have the problem? The blowers get their power from relays 6 and 7 with control signals from the HEVAC. The recirculate flaps, as you rightly say, are powered from the HEVAC but it doesn't use a transistor it uses an L272M dual op amp to drive the motors one way or the other. The same system is used for all the blend motors so if you look inside a HEVAC, you will see the 5 op amps, one for each blend motor. They are blend motors the same as the others but without the feedback pot. So I'm not sure how you can get a loss of permanent power as there isn't any, they are only powered when they are commanded to move which would suggest the fault is the permanent power to the blowers. Do they work?

Hi Gilbert,
yes the blowers work. It is the recirc. motors that come up on the scan tool as 'loss of power, permanent fault '. I am feeling a little better tonight after the operation yesterday. So I will plug the scan tool in after a good nights sleep and clear all the faults and see what comes back. I am reluctant to start crawling around under the dash as I don't want to pull any stitches out of my back. The Doctor was very clear about going home and doing nothing at all. But plugging in the scan tool should be OK. I will let you know what I find, as I did clean the connection to the left side recirc. motor. Interested to see if that made any difference.
Regards,
Alan

Yes, I guess your doctor would not consider fixing up the P38 among his preferred therapy options .... get well soon!!! :-)

Sounds like me, I stopped on the way back from hospital once, had just had tendon repair after a slip with a grinder, carrier bag over hand and I’m under a car 😂😂,
Take it easy my friend, it’s not going anywhere and if you pull the stitches your be cursing..

Hi Lads, thanks for your kind words. I have been tinkering with the Rangie, but not doing anything that might pull stitches. The first time I had skin cancer cut out of my left leg I tried to do too much, I pulled most of the 36 stitches and I got it infected. Doctor was not happy. I was digging a trench to run power, water and data to my shed. Working in the rain and mud. Dumb shit, in hindsight. I now have the biggest ugly scar to remind me to take it easy, when the doc says to take it easy. I have 3 more skin cancers to get cut out after this one heals up so I am going to be off work for a while yet. This is the punishment you get for spending your younger days fishing, crabbing, swimming, surfing, diving and just spending too much time on the beach in the sun. But it was fun.
Regards, Alan

Hi folks, today I though I would tackle the SRS light that stays on. How hard could it be. First I cleaned the plugs for the 2 air bags. Light was still on. next I cleaned the connector behind the R/S kick panel. Light was still on. Then I cleaned the connections on the 2 crash sensors under the bonnet. Light was still on. Next I went looking for the SRS module under the console allegedly. I ended up going to where I have my parts car and followed the yellow cable to the back of the console and there in a secret spot, under the insulation, known to Range Rover assembly line workers is hidden the air bag module. So tomorrow I can clean wiring plug and the module connections. If that does not fix the problem then the only thing left is the clock spring. Could the clock spring be faulty when the horn and the stereo controls all work as they should?
Regards, Alan

SRS on pre-99 model needs to be reset with diagnostics after you've cleared the fault. Later ones cleared as soon as the fault was removed, early ones didn't.

Hi Gilbert,
Thanks for that. I did read somewhere that the light would go out after you had cleaned the faulty connection. I will go and plug the scan tool in and see if the light stays off after I clear the fault.
Regards,
Alan

Hi Gilbert,
my SRS light is now out. Thank you very much Gilbert. I am now back to the EAS. I will reset all the heights tomorrow morning and see what happens then. I think I may be getting close to running out of things to do. I might go out and buy a UHF two way radio tomorrow and fit that while I have the lower dash panels off. That will keep me busy for a couple of hours.
Regards, Alan

Alan, you run a P38, there'll never be nothing to do!

Best of luck with the ops and, more to the point, the recovery. Take it easy.

George.

Hi George,
thanks mate. I did a bit too much today so am feeling a but second hand tonight. Maybe a easy day tomorrow. I have now fixed all my electrical gremlins, and thought I was close to finished then I found both head gaskets are leaking oil. Bugger. I am going to retorque them and see if that fixes the leaks. Otherwise it is both heads off and new gaskets. This is on a new motor with less than 50 kilometers on it. Block was decked, heads skimmed, MLS head gaskets, ARP studs and nuts. So I am at a loss as to why they have started leaking.
Regards,
Alan

Later 2 wheel tc abs ecu will work no problem on earlier non tc cars. Obviously not vice versa.
Later 4 wheel tc has different connectors.

Hi Tanis,
Yes thanks for that. Everything seems to be working fine now that I changed the Wabco computer. Did the 1995 P38 not have any traction control at all ?
Regards,
Alan