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Discussion Starter #1
Testing the solenoids is easy.
  • Unplug the multiplug at the front of the EAS box.
  • Connect the 12V & GND pins to the car battery
    • Pins 12+13 are 12V
    • Pins 10+11 are Gnd
  • Connect each pin 1 to 6 in turn to 12V
    • 1-4 are the corner valves
    • 5-6 are Inlet & Exhaust
The EAS ECU simply switches each of these from 0V to 12V to trigger the valves. The driver pack then converts these 0-12v signals to the modulated pulses for the solenoids.

Read the EAS System Info document for full description. It's a 1.2MB PDF that I cannot attached in this forum, but I did upload it to Landyzone.
I'm finishing up my EAS conversion with the only issue remaining is an 'Exhaust valve stuck closed' message. While researching possible causes I found this thread that matches my issue exactly.

So pins 12+13 should have wires run directly to the positive connector on the battery. Pins 10+11 should have wires run directly to the negative connector on the battery. To then test a solenoid, let's take pin 1 as an example which is the rear left valve. To test it I would connect a wire to pin 1 and the other end of the wire to what? The pos terminal on the battery?
 

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Discussion Starter #2
How does the EAS know a solenoid isn't responding correctly if the valve driver pack lacks a signalling mechanism back to the EAS? Lack of continuity?
 

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Yes, connect the individual pins for each solenoid to battery positive, you'll hear them click. If you also use one of the emergency Schrader valves and a short length of pipe, you can pressurise each outlet and the pressure will release when the solenoid opens.

The EAS ECU only knows that something that should have happened didn't. If the exhaust valve was stuck closed then no matter which corner solenoid was opened along with the exhaust valve, then the ECU would expect to see the relevant corner drop from the height sensor. If it doesn't drop when only one corner solenoid is stuck closed (or not opening when told to) so it would flag as FL or whatever, stuck closed. If no corner drops when the respective corner valve and the the exhaust valve opens, then it assumes it is the exhaust valve that is stuck closed. There's no feedback just an assumption on what is happening compared with what it thinks should happen.
 

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Discussion Starter #4
Yes, connect the individual pins for each solenoid to battery positive, you'll hear them click. If you also use one of the emergency Schrader valves and a short length of pipe, you can pressurise each outlet and the pressure will release when the solenoid opens.

The EAS ECU only knows that something that should have happened didn't. If the exhaust valve was stuck closed then no matter which corner solenoid was opened along with the exhaust valve, then the ECU would expect to see the relevant corner drop from the height sensor. If it doesn't drop when only one corner solenoid is stuck closed (or not opening when told to) so it would flag as FL or whatever, stuck closed. If no corner drops when the respective corner valve and the the exhaust valve opens, then it assumes it is the exhaust valve that is stuck closed. There's no feedback just an assumption on what is happening compared with what it thinks should happen.
Much thanks. Will report back.
 

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Assume you are looking at this connector rather than C117 under the seat from those numbers. You can also jump valves and the compressor from C117 to add air if hard faulted. Also, a stuck valve error can come from toasted driver block, happened to me and drove me nuts for awhile.
 

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Discussion Starter #6
Went through yesterday and tested the driver pack and the solenoids. Sure enough the 'Exhaust valve stuck closed' error was due to the driver pack and not the solenoid. Thankfully the driver pack off my parts vehicle was good so I got the satisfaction of finding the error and fixing it. After driving around all today the error hasn't returned and the vehicle has been height adjusting without any issue.
 

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Nice work, good to have spares. This issue is how I purchased my P38 with 28k miles on it in '05. The previous owner's wife had been through 2 or 3 hard faults on the freeway and didn't want to drive it anymore. It was into the dealer multiple times but error was intermittent. Finally off warranty, they dumped it. For the price of a replacement driver block I got a low miles P38 for cheap.
 

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Discussion Starter #9 (Edited)
Just to add to Richard's post, here's the "EAS fault message" details from the EAS SID.
Helpful. Thank you.

If the driver pack is there just to convert a bunch of 12v dc signals to a bucnh of 12v pwm signals of a certain duty cycle, if we treat the driver pack as a black box with inputs on one side and outputs on the other it would be straight forward to model that behavior as a first step to designing a replacement. What I'm saying is we don't have to bother learning to repair old driver packs, we can just replace them.

That said, I'm about a year out before I'll have the time to start this though so perhaps one of the retired gents could have a go. :geek:
 

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New Dunlop drivepacks are available for less than €250, so not sure if it's worth trying to reengineer it.
 

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That's correct, the driver pack converts 12V signals but not to PWM but to peak and hold so gives a blast of high current to pull a solenoid in quickly then drops the current to hold it in (to stop the solenoids overheating and burning out). Marty did build a replacement a couple of years ago using more modern components which worked perfectly until it got very hot then it shut down on him. It's one of his projects that probably will get dragged out if he gets really bored.
 

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Discussion Starter #12
ah just assumed they were NLA
 
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