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Discussion Starter #1
What's my RR trying to tell me?

4.6 Auto 1998 GEMS

For the last few days, the gear selection light sometimes read differently from the physical position of the lever, but whatever the light says is also the reading on the dash.

After the first time I saw it I put the battery on a trickle charge overnight, until my charger went to "maintain" status. (The Bosch S3 battery is six months old, and as a precaution every month or so I have charged it fully using a trickle charger, so I expect it to be in a decent state.)

Then yesterday evening it repeated the gear selector issue, alongside a failed start, where it usually starts on the nail. I turned off all electrics turned on the ignition, and it reluctantly started.

I didn't have much time today, but running the engine at 2k rpm the voltage drop from battery to inlet manifold was only 74 mV. Despite that being less than 130mV in the official troubleshooting guide, I removed and cleaned the earth points (they didn't really seem corroded though). Battery voltage is 14 V, and if I turn on all electrics without the engine that comes off to 13.85V

After a drive this evening, the selector issue is still there, although the engine has fired fine for the last couple of starts.

Can any P38 whisperers suggest the next plan of attack?

Thanks, Rob
 

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Failing gear position switch (XYZ Switch) on the side of the gearbox. It uses 3 switches arranged in a matrix to send the gear position to the dash message centre and lights next to the lever. If one switch fails then some gears will display correctly while others won't. It becomes a bigger problem if P or N don't display correctly as it will only start if it is in one of those. The XYZ switch is simple enough to remove and although it is riveted together it is a fairly easy job to drill out the rivets and get inside to see if it can be repaired. Usual cause of failure is the breather hose falls off and as it is directly above the AC drain gets filled with water which rots the tracks inside. I've repaired them by soldering jumper wires in place of the rotted tracks, it's fiddly but a replacement isn't cheap.
 

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Discussion Starter #3
Thanks Richard - is that the "inhibitor switch" in RAVE parlance? Yes , looks v. pricey. Sounds like it's not a job to be put off for very long, I'll strip it off and see what
I've got
 

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No, the inhibitor switch is something else, RAVE describes it as the Selector Position Switch in the Auto Gearbox section of the Workshop Manual and as the XYZ Switch in the ETM. RAVE also suggests using a special tool to align it when you put it back but if you mark the position before slackening off the two fixings (one 10mm bolt, one 10mm nut) you can get it back in the same position when it goes back on.
 

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Discussion Starter #5
thanks Richard, helpful as ever
 

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1995-2002 Range Rover P38A
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It could be failing switch if it's showing weird values - but also worth checking the selector cable for adjustment - if it's gone slightly slack, then that can also cause it to show the wrong gear.

They are riveted together, but I have had success before in drilling the rivets, opening the switch up and cleaning the contacts/old dried grease, and reassembling. From what I understand it's still working OK - it was for another owner, but I'd be popping mine open if I ever got issues with it.
 

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Discussion Starter #7
Just to close this one down.
Symptoms: failed to start periodically and just gives a solenoid/ no starter flicking sound after turning the ignition switch
Temp fix: if the selector light doesn't display park, then run through neutral/ all positions to see if you can find the neutral light to start the engine and fool the becm into thinking you're in neutral.
Problem: It was indeed my xyz switch, opened it up to find a fair bit of water/ condensation inside. Breather disconnected (find a small section of pipe to connect to the small hole next to where the wires emerge from the body of the replacement switch)
Top tip - watch the exact ZF part number - my 1998 used ZF 0501 210 740 plus a grey connector. Breakers will sometimes just say "grey connector", but that's not enough 0501 211 036 is also grey - the wiring will fit, but the aluminium shell of the switch body is taller than on the 740. I suspect other posts referring to breaking the switch when trying to tighten it up were this exact issue.

Thanks to Richard G for multiple PMs to help me out on this - most of the above wisdom is his
 

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1995-2002 Range Rover P38A
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No, the inhibitor switch is something else, RAVE describes it as the Selector Position Switch in the Auto Gearbox section of the Workshop Manual and as the XYZ Switch in the ETM. RAVE also suggests using a special tool to align it when you put it back but if you mark the position before slackening off the two fixings (one 10mm bolt, one 10mm nut) you can get it back in the same position when it goes back on.
Hi,
How do you set it up (without special tool), if you forgot to mark or replacing with another one?
I'm replacing my HP22 with a HP24 and it came without XYZ switch. I got to fit it with the HP22 one.

thanks in advance.
 

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Discussion Starter #9
I didn't mark the settings, and had no issues. If you have trouble you can use an assistant in the RR above to tell you when the physical selection matches the light, and then tighten up. I even got back the selection of First (presumably where the adjustment had been poorly done previously)
 

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I have a problem with the XYZ switch. When moving the shifter from P to 1, it jumps from R to D without showing N. Then moves to 3 and stays there when the shifter goes to 1. Tried adjusting the shifter cable but no luck.
The XYZ switch was working perfectly when it was with the HP22 box.
 

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They are particularly fragile, what does it show compared with the position of the lever? If you have it showing P and 1 correctly, then it is adjusted right but if it isn't showing N, what does it show when the lever is in N position. Same for the other gears.
 

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Here are the positions;

Shifter Shifter LED Dash indicator
P P P
R - P
N R R
D R R
3 N N
2 D D
1 D D

(It's bit tight to get to 1 )
Your views please.
 

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That makes no sense at all. For it to show P when in R, you would need the Y switch to be open circuit, yet if that was the case, D would show 1, 3 would show 2 and 2 would show 3. Can you test the outputs from the switches with a meter?

Check the X switch by connecting the meter between pin 1 and 6 on the connector. That should give the following:

P, Short Circuit (SC)
R, SC
N, Open Circuit (OC)
D, OC
3, OC
2, OC
1, SC

The Y switch is across pins 2 and 6 and should give

P, OC
R, SC
N, SC
D, SC
3, SC
2, OC
1, OC

and the Z switch is across pins 3 and 6 and should give

P, OC
R, OC
N, OC
D, SC
3, SC
2, SC
1, SC

If the switch tests OK, then is it possible you have trapped or damaged the loom between the switch and the rest of the car while changing the gearbox?
 

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I had exactly same issue with mine about 7yrs ago. I had a new mech look at it. He first replaced the cable ("probably old and worn"), then he had the gear box reconditioned; still very dodgy after all this. 4 mths later my orig P38 whisperer set up shop close to work. Dropped it off in morning, drove away at end of day. He did whatever 'adjustment' you need to do to the cable, and I have not had a problem since. Occasionally I have to use some force to get into P. My whisperer told me at time you just gotta know how to set the 'adjustment'. Said it didn't take long but if I had any ongoing issues then would have to look at new inhibiter switch. Don't have a clue how he did adjustment. He just knows how to do it. I'll get some details next time i see him. The truck needs some attention to the cruise control.
 

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Thanks Richard G.
I was playing with the shifter and got it to N (dash showing R) and again push it to R . Then it read R in both places. Likewise did for all others but no change in N,3,2,1, positions. 3-1 always show D & N position the LED just jumps onto R or D. The car drives okay except mismatch in the cluster & the shifter.
There is no chance of wiring harness dangling with the box, I kept all away and made sure that didn't happen.
My multi-meter is not working and need to buy one to do the tests.

Also noted that the shifter cable shows a S bend in the middle whereas I can't remember such thing with HP22 in place. Are the cables for HP22 & HP24 different? petrol vs diesel?
 
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