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Discussion Starter #1
Hi Guys. My problem is that my diaphragm solenoid on the valve block is not responding.This is allowing air from the compressor to pulse through the exhaust silencer. I have a pressure gauge teed into the airline from the block to the reservoir /tank. This would not get higher than one 15lb as it kept venting.
The valve block has just been rebuilt and is spot on. I also have a new driver unit fitted to the valve block. Ive used the rave wiring diagrams and checked the power supply to the diaphragm solenoid. I know that it should be 12v from the compressor relay (when compressor is running) through the solenoid to ground. I have 12v showing on both sides of the solenoid. I cut the cables to it and checked both cables.
Can anybody suggest how this maybe possible as I cant work it out. I am using the eas 4 software and cable to communicate with the EAS control unit.ds of
BTW as soon as I hotwire the cut ends of the solenoid to power and ground, I can run the compressor up and fill the tank with no exhaust silencer air venting.

here's hoping :? as ive searched for hours and can not find a similar thread.
 

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Do you have RAVE ? If not download it.

Sounds like the 0V ground side of the diaphragm solenoid is disconnected somewhere ? As you have discovered, this solenoid is not driven by the driver-pack. Check continuity through the various connectors, i.e.


  • Pin-8 on main EAS Box connector to Pin-1 on connector between driver-pack & solenoids.
  • Pins-10/11 on main EAS Box connector to Pin-2 on connector between driver-pack & solenoids.
My guess is a bad connection on Pin-2 in Connector C142. The housing will be tight, but the contacts often don't make good connections. I have resolved many EAS faults by squeezing the 12 sockets to make better contact with the pins.

Screen Shot 2018-02-15 at 17.57.11.jpg
 

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Discussion Starter #3
Many thanks pwood999.
I will check all you suggested and report. BTw yes I do have Rave and found the same diagram that you kindly included. My fault description was poorly described by me in one respect. The 12v that I recorded at connector c142 should have been described as follows - diaphragm solenoid disconnected and pins 1 and 2 both supplying 12 volts. From the diagram I believe it should be 12v supply to one pin and the other going to ground.
regards
 

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Did you measure 12V across the 2 pins of C142, or was there 12V from each pin to ground?
 

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So fix C142 Pin-2 first, and make sure it has good connection to Pins-10-11 on the main EAS housing connector. Also check the ground splice S151 which is somewhere inside the EAS box as well.

Then the diaphragm valve should operate when the pump runs.
 

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The splice is buried in the wiring (from memory) just outside the driver pack, and is encased in heat shrink with hot melt glue all through it - so it's unlikely to be the splice I would think.

What voltage do you read between the 2 pins on the loom side? (when the compressor is supposed to be running)
What resistance do you measure between the 2 pins on the solenoid side? (should be about 3-4 ohms from memory)

I'm struggling to work out how you can measure 12V on both pins to ground (were the connectors unplugged or did you probe the wires?) when one of them is spliced into the other ground wires and goes straight to a ground point. Even with a break in the wire that's supposed to go to ground, it would read nothing.

My best guess is that as pwood999 says, either a dodgy pin in the female side of the connector, or possibly a bad solenoid coil.
 

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Discussion Starter #8 (Edited)
Hi Guys. Firstly ,many thanks for your support and suggestions.
ok- I followed your recommendations.
so far I proved that c142 has a good clean tight connection point at pin 2. The diaphragm valve did not open.
The diaphragm solenoid was replaced with a new one from island 4x4.
I measured the voltage from each pin on c142 with the compressor running. The green cable showed 14.3v and the black showed 12.5v which then slowly climbed to 13.73v. I believe it would possibly have kept climbing.
I checked the pressure switch using the procedure read on this forum- all correct.
I checked the compressor overheat sensor using the same procedure read on this forum-all correct.
I swapped over the compressor relay with another one from a working circuit on the fuse box under the bonnet.- no change in fault. (this fuse box is only 8 months old and dates back to my trying to fix a popping noise on all the speakers.Turned out to be the original head unit that was in the car.)
Checked the connectors in both foot wells. Found corrosion on all- I cut them out and replaced them all except the speaker connector in the left side. Fault still there.

I dropped the left side upper foot well odb2 holder. Found corrosion in the connector. I have a new one on order. temporarily I have made up a set of insulated cables to connect the odb2 cable from RSW solutions manually pin by pin. I did note all the pin positions and copied them when manually connecting the cable. I have RSW product 3 ,the old eas only module and the RSW4 new cable and software that allows connection to extra modules.
Previously I could establish connection to the eas using RSW3 but not RSW4 . RSW4 would let me connect to all the other modules ABS, engine etc. Now none will connect to the eas. The dash does report connection and disconnection with script and an audible signal when the usb end is plugged into the laptop or removed from it.
I have replaced the eas driver unit on the valve block with a new one from island 4x4- fault the same.
I have checked the ground points indicated in RAVE -all good.
I have checked the ground pin in the odb2 wiring for continuity and also the ground pin in the eas ecu connector -all good and no voltage.

When the new odb2 connector arrives I will install it and report. it should have been here for sat/sun but thats life.
I am using http://paulp38a.com/range-rover-p38/how-eas-works/ and RAVE as my reference material for wiring.

btw I am not a guy to give up so your kind input is very welcome. regards

p.s I have read that the solenoids on the valve block should not have 12v put through them for an extended period but the same part no is used on all the valves and the diaphragm solenoid appears to be wired to receive just that?
 

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Discussion Starter #9
sorry. I have done so much. I forgot to add-
I have trimmed the internal rubber on connector c117 to reduce the thicknes by 2/3 mm to ensure better depth of connection to the eas ecu and I have also tried a back up ecu I bought from my trusted Range rover breakers in se7.
 

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Discussion Starter #10
hi Guys
Maybe I am wrong but I think I have had a eureka moment. I think I am showing voltage on the ground pin from the diphram as its the regular ground thats the problem. Update you soon as I can get on the car. regards
 

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You are correct about the main solenoid valves do not use 12V, but instead the driver pack supplies a modified waveform.

BUT the diaphragm solenoid is definitely 12V together with the pump feed. The solenoid is wound differently so can withstand the continuous voltage.

Even if the driver pack is disconnected, you can power the pump & diaphragm valve, and the tank will fill through the NRV. All the other valves are ideally closed during filling, which is why we recommend leaving drivers door open to disable the inlet & corner valves. Exhaust must be closed during pump operation because the air routes through the block are mutually exclusive for filling to work.
 

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