P38A A series of faults

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
No fault codes, suspension only goes up. If you tell it to go down nothing happens, unless you short the exhaust solenoid which then makes it open.

My understanding is that the solenoids are energised on both sides at idle but not powered (so they can react quickly) and then the 'drop' signal goes to it them they open.

The suspension ECU is sending the correct signal to the Exhaust Solenoid input to the Driver Pack, but there is nothing coming out the other side as it were
 
IMG_2849.JPG
Slooby said:
No fault codes, suspension only goes up. If you tell it to go down nothing happens, unless you short the exhaust solenoid which then makes it open.

My understanding is that the solenoids are energised on both sides at idle but not powered (so they can react quickly) and then the 'drop' signal goes to it them they open.

The suspension ECU is sending the correct signal to the Exhaust Solenoid input to the Driver Pack, but there is nothing coming out the other side as it were
Click to expand...
They are not pre energised, they use "pick & hold". The solenoids are 9 volt, they are hit briefly with 12 volts followed by a pulse train that holds them.
The contacts in the connectors become loose and go open circuit. I have never seen a driver pack with a failed output circuit, of course it may happen, I have just never seen it despite seeing and repairing a few.
Check the diaphragm valve and also check for white powder in the valve block.
 
Last edited:
So we were seeing just under 14V at the connector to the Driver Pack on the Exhaust Solenoid pin coming from the EAS ECU, but on the output from the Driver Pack there was no current draw (1 amp being what we saw on the Inlet and individual air spring solenoids when they fired using a decent Fluke Clamp Meter) going to the Solenoid (I think that's how my mate described it, I was looking for info at the time) on the Solenoid.

We did continuity check each connector pin for tge solenoids and driver pack in the hope that could be the problem, but they all seemed good. Grounding tge Exhaust Solenoid showed that it was working. This is why we were looking at the Driver Pack itself and suspecting that one of the Fet's had died on the power side for the non firing solenoid.

Is there anything we've missed? My electronics diagnostic skills are somewhat limited compared to my mate who has gone back home to Tadley now with his Clamp Meter and Scope, so words of one or two syllables and instructions for an 8 year old please ;)

I've started looking to try and pick up a complete spare EAS pump/valve block unit to cannibalise for parts just in case it could be as simple as swapping out the driver pack

The two of the NRV valve aluminium cones that are the same orientation are quite worn on, but one would have thought that would just cause leaks rather than stop them from opening
 
IMG_2860.JPG
Slooby said:
So we were seeing just under 14V at the connector to the Driver Pack on the Exhaust Solenoid pin coming from the EAS ECU, but on the output from the Driver Pack there was no current draw (1 amp being what we saw on the Inlet and individual air spring solenoids when they fired using a decent Fluke Clamp Meter) going to the Solenoid (I think that's how my mate described it, I was looking for info at the time) on the Solenoid.

We did continuity check each connector pin for tge solenoids and driver pack in the hope that could be the problem, but they all seemed good. Grounding tge Exhaust Solenoid showed that it was working. This is why we were looking at the Driver Pack itself and suspecting that one of the Fet's had died on the power side for the non firing solenoid.

Is there anything we've missed? My electronics diagnostic skills are somewhat limited compared to my mate who has gone back home to Tadley now with his Clamp Meter and Scope, so words of one or two syllables and instructions for an 8 year old please ;)

I've started looking to try and pick up a complete spare EAS pump/valve block unit to cannibalise for parts just in case it could be as simple as swapping out the driver pack

The two of the NRV valve aluminium cones that are the same orientation are quite worn on, but one would have thought that would just cause leaks rather than stop them from opening
Click to expand...
I'll take a close look at the diagrams but it will be tomorrow before I can get back to you.
 
No worries it's dark now and I'd have to de-pressurise to get tge valve block off to unbolt the Driver Pack.

Also loctiting all the bolts securing the valve block together and the Driver Pack to it when I rebuilt it has resulted in one sheared cap head from tge Driver Pack mount :/
 
Forgot to say when I opened up the valve block to check that I had put the NRV's back in the correct order during the rebuild (I had) there was no sign of any desiccant powder inside. I replaced the desiccant in the drier unit as part of the valve block rebuild (all new seals and diaphragm) and blew degreasent through the lines from the spring ends back before refitting the valve block.
 
Slooby said:
Forgot to say when I opened up the valve block to check that I had put the NRV's back in the correct order during the rebuild (I had) there was no sign of any desiccant powder inside. I replaced the desiccant in the drier unit as part of the valve block rebuild (all new seals and diaphragm) and blew degreasent through the lines from the spring ends back before refitting the valve block.
Click to expand...
Not much more I can say to help except applying 12 volts to the solenoids for any length of time can be destructive. Also I doubt you would see anything on the solenoid drive lines with a clamp meter.
I don't like the sound of "degreasent" the block airways should be dry.
Thread lock is not needed IMO on the valve block screws, at least I have never used any and the first valve block I did is still OK a decade later.
Not seen any case of dry joints on the valve block PCB wires or components, only contact failures. There is one component that is a common failure but it would not affect exhaust valve operation.
 
I used brake cleaner and my air compressor to blow through the plastic air lines on the car then left it 24 hours before plumbing everything back in. It was just a precaution as it had been stood disconected for months, granted with the line opening taped over, but just in case.

I've just learnt the hardway that threadlock, even the weaker version, was too muck for the cap head S/S screws holding the Driver Pack on. The heads of three out of the four have sheared, despite focused heat on them from a hot air plastic welder :( Each screw that came out had had 'dry' threadlock applied to them (the blue substance on the threads) hence me cleaning that off and puting a spot of liquid threadlock on each. Even that was too much clearly.

The potting around the wires where they go into the Driver Pack has cracked, I'm looking at it all now in closer detail for signs or corrosion or damage
 
Slooby said:
I used brake cleaner and my air compressor to blow through the plastic air lines on the car then left it 24 hours before plumbing everything back in. It was just a precaution as it had been stood disconected for months, granted with the line opening taped over, but just in case.

I've just learnt the hardway that threadlock, even the weaker version, was too muck for the cap head S/S screws holding the Driver Pack on. The heads of three out of the four have sheared, despite focused heat on them from a hot air plastic welder :( Each screw that came out had had 'dry' threadlock applied to them (the blue substance on the threads) hence me cleaning that off and puting a spot of liquid threadlock on each. Even that was too much clearly.

The potting around the wires where they go into the Driver Pack has cracked, I'm looking at it all now in closer detail for signs or corrosion or damage
Click to expand...
The potting always cracks where the wires go in. If there is cracking in the potting on the edge to the right of the cable entry, then it's likely the electrolytic has failed but it would not stop the exhaust valve working.
Just a thought, applying 12 volts to a 9 volt solenoid may cause a sticky armature to move that would not move with the standard signal.
 
In Wammers guide he linked to a copy of the O/E Land Rover System Information Document: http://p38a.net/p38a/2014/01/04/EAS - System Information Document.pdf

That shows that one of the wires to the Solenoid is at 12V, while the signal 'Hit and Drop' sue to the waveform will measure at around 9V on a DVM. Which we saw. The calmp meter test on the solenoids that did fire showed a fluctuating current draw of between 0.5 and 1A when they fire and nominal when at idle. The Exhaust Solenoid was the only one that wouldn't fire when prompted to by the ECU

Going to post some pics in a sec of the potting...
 
Slooby said:
In Wammers guide he linked to a copy of the O/E Land Rover System Information Document: http://p38a.net/p38a/2014/01/04/EAS - System Information Document.pdf

That shows that one of the wires to the Solenoid is at 12V, while the signal 'Hit and Drop' sue to the waveform will measure at around 9V on a DVM. Which we saw. The calmp meter test on the solenoids that did fire showed a fluctuating current draw of between 0.5 and 1A when they fire and nominal when at idle. The Exhaust Solenoid was the only one that wouldn't fire when prompted to by the ECU

Going to post some pics in a sec of the potting...
Click to expand...
Yes the solenoids are switched on the negative line and the wave form results in an average voltage level of 9 volts
I will be interested in what you eventually find as I have not seen a driver pack with a failed drive transistor.
 
Yeah, going to keep rumaging, but without my mates here who are full on electronics people I am way out of my depth! Got quite the e-mail trail going with them all, one of them is seeing it as an excuse to get a hot air re-work station...while another already has one!
 
You definitely do NOT need loctite on any of the screws in the valve block. It just makes it more difficult to refurbish.

As said many times before the usual culprit of 1 or 2 solenoids not operating are the contacts inside the connector from valve block to the solenoids. Cleaning them is only half the solution. The socket contacts lose their grip over time & become intermittent. The other main issues are what Keith said, i.e. bad electrolytic or dry joints on the wires entering the driver pack.

If you want to test the solenoids individually, use a 6v or 9v battery, but only tap the connection so you don't burn the coils. When disconnected, the coils should measure about 3.7ohms.
 
When we probed the back (pushing a ~0.5mm 'probe' past the rubber wire seal) of the connector pins and sockets on each side of the connector block we found good continuity on the ones we tested, especially the wires for the Exhaust Solenoid

From what you are both saying I need to go have a dig around in the potting around the wires where they join the Driver Pack. I can identify the right colour wires for the output, but not input side of the driver pack as the connector guides don't actually reference to input side :/
 
Before digging at the driver pack, check each solenoid operates using a 9V battery. A short tap of 9V should make the solenoid click.

btw, RAVE does include the wire colours for input & output of the driver pack.
 
We did have all the solenoids firing yesterday when testing the direct. It was only the Exhaust Solenoid that wouldn't respond to a command from the ECU. The signal was getting from the ECU to the Driver Pack, however there didn't appear to be an out put from the Driver Pack to the Exhaust Solenoid.

I'll dig out a 9v battery and give direct firing the solenoids a try. Would it also work through the Driver Pack?

Cheers for the tip about RAVE I'll go take a look
 
Datatek said:
DO NOT flash the driver pack with any sort of battery.
Click to expand...

Roger

I've just run through all the solenoids through their connectors (the 13 way for the main 6 and the 2 way for the Diaphragm) with a 9V battery and they all fired just fine, so the Valve pack itself *should* be ok

Datatek said:
The pins come out of the connectors quite easily it's always possible that the wire has broken at the pin crimp.
Click to expand...

I was just about to have a dig through RAVE to find the wiring guide for the input side of the Driver Pack so that I can run a continuity check through it, assuming that there is a direct feed through it of course

Datatek said:
Or you could buy a spare, not expensive:-
https://www.ebay.co.uk/itm/304058835136?hash=item46cb51a0c0:g:raAAAOSwl75Zt8Im
Click to expand...

Indeed, that one is on my watch list...

As is this:

https://www.ebay.co.uk/itm/294702946129

Yes, it looks like it's been in a swamp, but the seller claims it was working fine before they broke the RR and it is just up the road from me so I could potentially get it tomorrow as I have the day off. It would also give me more sapres just in case.
 
You must log in or register to reply here.

Similar threads

R
Brakes having an episode 🤦🏼‍♀️
Replies
10
Views
371
Datatek
Datatek
kricktd5
L332 abs/ HDC
Replies
1
Views
484
Datatek
Datatek
pwood999
P38A EAS Random Extended Mode Selection
Replies
11
Views
385
pwood999
pwood999
I
L322 ABS query
Replies
0
Views
599
isamyku
I
JamesBB
P38A Unrepairable EAS fault after side steps fitted?
5 6 7
Replies
128
Views
7K
pwood999
pwood999
Back
Top