P38A 97 P38 Gems - EAS issue which seems to have expanded

Battery fully charged, start it and run it for a while. Clear all faults, run it over 5 mph until lights on dash go out and then check faults again.

Most if thise faults look like ghosts from low volts. Could be bad earth somewhere, possibly under the fusebox. Did Tomcat mention an issue with the plug under the expansion tank once causing odd issues?

If the RSW software is communicating at all then I would guess the delay relay is probably OK as they rarely fail and if they do then it won't talk to the EAS. You can stick a standard automotive relay in instead and the EAS will work but it won't allow diagnostics to talk to the EAS ECU.

Grrr, Good to 'hear' from you again.
Rainy / sneaky on and off days here for a couple.

Will try that - Though I'm going to get the RR height sensor issue as the casing broke when I went to went to take a closer look.
Teaches me, dont touch some "shad" until you have replacement part in hand.
Will that abort the effectiveness of the RSW retest?

No I didn't catch the plug under expansion tank issue / will check

The delay relay question comes from the one repeated RSW fault reported ABS Fault 1,2,8 - no voltage at ECU Pin 1 when ignition on
My schematics show the ECU pin 1 power source is the delay relay -
And if that is actual case then may that be messing all of this up with a domino effect as it were?
Or is it in its self a "ghost fault"
Brake switch fault
Pressure switch fault
RR ABS gap to large
Fuel temp switch high range fault (driving cycle A)
Transfer box link - signal permanently at ground (driving cycle A)
Then height sensors FL / FR / RR go on and off between tests - FL has disappeared completely

But tomorrow I will check the plug and what it looks like under fuse block.
Then run the truck and around the block - roads are at least decent so it wont be a terrible ride - and report back.

Just drives me a little batty that I go 4 yrs with virtually nothing or not an impact - a door lock to replace or like.
And then I have to get Black box BECM and EAS Kicker to correct the preceding issue. Then EAS craters and RSW gives me a sequence of faults, but.

Thx - Cheers,

Certainly I would chase the faults it is telling you. Not used the RSW software as I have a Nanocom. Should be easy to check pin 1 and where it gets its power should be in the diagrams in RAVE. It might be the OBD port. Check for green, front and back.

frozen north 2 said:

Grrr, Good to 'hear' from you again.
Rainy / sneaky on and off days here for a couple.

Will try that - Though I'm going to get the RR height sensor issue as the casing broke when I went to went to take a closer look.
Teaches me, dont touch some "shad" until you have replacement part in hand.
Will that abort the effectiveness of the RSW retest?

No I didn't catch the plug under expansion tank issue / will check

The delay relay question comes from the one repeated RSW fault reported ABS Fault 1,2,8 - no voltage at ECU Pin 1 when ignition on
My schematics show the ECU pin 1 power source is the delay relay -
And if that is actual case then may that be messing all of this up with a domino effect as it were?
Or is it in its self a "ghost fault"
Brake switch fault
Pressure switch fault
RR ABS gap to large
Fuel temp switch high range fault (driving cycle A)
Transfer box link - signal permanently at ground (driving cycle A)
Then height sensors FL / FR / RR go on and off between tests - FL has disappeared completely

But tomorrow I will check the plug and what it looks like under fuse block.
Then run the truck and around the block - roads are at least decent so it wont be a terrible ride - and report back.

Just drives me a little batty that I go 4 yrs with virtually nothing or not an impact - a door lock to replace or like.
And then I have to get Black box BECM and EAS Kicker to correct the preceding issue. Then EAS craters and RSW gives me a sequence of faults, but.

Thx - Cheers,

Click to expand...

The EAS delay relay has nothing at all to do with the ABS.
Most of those faults sound like low battery volts.

+1. Egg sack arry.

Rubberknees said:

Found it Nissens 70220 heater exchange unit

Click to expand...

While I wait on other parts arrive on carrier pigeon it seems.
Is the nissons 70220 a more direct fit than the Audi one PaulP38 referred to?
It is more readily available than some options from Partsavatar $154.00
And its in line for $ than a couple other direct OEM options out of the states - longer time lines.
I'm just going to have to loop the rad supply lines - cleaned up from the leak but still have to get EAS going.
Cheers,

frozen north 2 said:

While I wait on other parts arrive on carrier pigeon it seems.
Is the nissons 70220 a more direct fit than the Audi one PaulP38 referred to?
It is more readily available than some options from Partsavatar $154.00
And its in line for $ than a couple other direct OEM options out of the states - longer time lines.
I'm just going to have to loop the rad supply lines - cleaned up from the leak but still have to get EAS going.
Cheers,

Click to expand...

The 70220 on mine slid straight in without the faff off all the cutting. UK price was £20 including delivery

Well I'm western prov's of CA / colonies - must be nice - you have parts availability and price advantage.
Probably 90% of our decent parts choices / used / new / original / vehicles come out of the deep south states TX -Flr - Ark.
So get tapped on exchange rate and postage - almost as expected for straight from UK
So with Nissons - avoids O rings / piping extensions and just get longer 1" rad hose to connect direct I assume?
Thx for the clarification.
Cheers,

frozen north 2 said:

While I wait on other parts arrive on carrier pigeon it seems.
Is the nissons 70220 a more direct fit than the Audi one PaulP38 referred to?
It is more readily available than some options from Partsavatar $154.00
And its in line for $ than a couple other direct OEM options out of the states - longer time lines.
I'm just going to have to loop the rad supply lines - cleaned up from the leak but still have to get EAS going.
Cheers,

Click to expand...

I cannot recall which one I put in but I think it was the bigger Nissens one. My thread will be somewhere on here. Only had to shave the ridge a sliver with a Stanley knife to make it fit.

Just an update -
Well, I looped the rad lines to matrix so I can run vehicle / continue EAS - will get back to "matrix" I've got to many bits / pieces / panels open - though some minor success would probably be a positive at this point.
Was tracing wire / connections for continuity / power - just validating "pathways" / removing possible problems.
RSW test indicates Pin 1 ECU plug pwr from delay relay - no power.
But there is power ( test to grnd) in key pos II and running.
At the same time RSW is indicating three height sensors are incorrect (no power?)
Cant really test continuity of height sensors - given nature of it as a rheostat(?) of type - but the height sensor does generate resistance.
So will retest for the resistance @ ECU plug Pin 21/23, 20/22 - (rear right HS broken and removed - so should be nothing), 3/5, 2,4 all return path to Pin 24
As RR HS it is broken & removed now and reporting as incorrect then I will take it as "incorrect" as no power / broken pathway.
Or the RSW is messing with me and RSW is reading something before this point in chain.
But if three are "incorrect" - though depending on RSW log FR reports on and off - so maybe the two right side.
So off schematics the only common path back to ECU plug from all HS to Pin 24 is through splice 116 - but 5000 pg manual doesn't indicate where splice is.
So also going through checking all the front half of earth grounds. Will pull, check wires to lug, clean, dab wire end with marine sealant, add some dielectric grease and reaffix. I think soldering these will make them to brittle unless necessary. But thtat should make them pretty predictable into the future.
Oh well will just keep investigating.

Cheers,

I think @Datatek or @pwood999 are the only ones who might know if that is correct or not. That delay timer does odd things and I don't know what effect it might have.

frozen north 2 said:

Just an update -
Well, I looped the rad lines to matrix so I can run vehicle / continue EAS - will get back to "matrix" I've got to many bits / pieces / panels open - though some minor success would probably be a positive at this point.
Was tracing wire / connections for continuity / power - just validating "pathways" / removing possible problems.
RSW test indicates Pin 1 ECU plug pwr from delay relay - no power.
But there is power ( test to grnd) in key pos II and running.
At the same time RSW is indicating three height sensors are incorrect (no power?)
Cant really test continuity of height sensors - given nature of it as a rheostat(?) of type - but the height sensor does generate resistance.
So will retest for the resistance @ ECU plug Pin 21/23, 20/22 - (rear right HS broken and removed - so should be nothing), 3/5, 2,4 all return path to Pin 24
As RR HS it is broken & removed now and reporting as incorrect then I will take it as "incorrect" as no power / broken pathway.
Or the RSW is messing with me and RSW is reading something before this point in chain.
But if three are "incorrect" - though depending on RSW log FR reports on and off - so maybe the two right side.
So off schematics the only common path back to ECU plug from all HS to Pin 24 is through splice 116 - but 5000 pg manual doesn't indicate where splice is.
So also going through checking all the front half of earth grounds. Will pull, check wires to lug, clean, dab wire end with marine sealant, add some dielectric grease and reaffix. I think soldering these will make them to brittle unless necessary. But thtat should make them pretty predictable into the future.
Oh well will just keep investigating.

Cheers,

Click to expand...

You can check the height sensors for resistance throughout their range with them disconnected using ohms on your meter. You can also check the signal with them connected, one end of meter to ground the other end to the wire going to the centre pin. I stick a pin through the insulation to make the connection.
I'd steer clear of the grease, it will cause you more problems in the long run.
Soldering will not make the wires brittle.

If RSW connects to the EAS ECU, the delay timer must be working. Assuming you have sensible faults, then carry on with the other resistance & voltage checks.

For the height sensors, Pins 20 & 21 are just a reference 5V supply. Sensor grounds all go back to Pin 24 on the ECU.
Pins 4, 5, 22, 23 are the return voltage to the ECU giving height values.

As Keith says, check each sensor through the entire range for both resistance (disconnected) & voltage (connected).

How it Works
F44 provides permanent 12V to one side of the relay.
F24 provides ignition switched power to close the relay & power the ECU during normal operation.
Pin 5 gets the self-levelling wake up signal from the BECM which also closes the relay.
Pin 1 on Diagnostic socket is used to flip the relay Off-On so the RSW can initiate the connect sequence. This is why the ignition must be on, before trying to get diagnostics to start.

Note: Always connect the RSW cables before switching ignition on. After doing diagnostics, always press the disconnect button in the software. Then switch ignition off, and wait 30 seconds. finally disconnect cables.

Thx Guys -will pour over this in detail when I get back to "this" tonight but,
Data.. the dielectric grease no? I had started to rely on that for power equipment at lake because of infrequent use or winter storage.
And has been a bit of a savior - not questioning per se but how is it a negative in this application?

Pwood, well I'm chasing the height sensor faults because they are the only "faults" that are reporting on RSW EAS
There are only 3 faults (RL RR FR) all HS - but the rear left HS falls off and on the log - the only two for sure are the right side.
But unless when I get past these HS issues will others will pop up as the system opens - if that happens?
But then at the same time - why would the blacbox EAS kicker resolve any intermittent issue before this cratered?
Unless 2 - 3 of the HS were failing progressively - Blacbox cleared faults - and finally the 2 - 3 failed pretty much all at once?

Also - if I run the rover or tests daily - I get the four flashing lights immediately before the four solid lights.
If I leave vehicle for a couple days - when I start the vehicle I get 2 lights - normal running height & passenger exit, then the four flashing and finally four solid.
Or maybe these "symptoms" don't imply anything?
But I'm trying to find replacement for all four corners HS - test as necessary (used / new) and throw those on and remove the "hardware" variables. But my options here are pretty slim.
If I switch to the new "OEM" china etc bit I have to press out and in the HS lower leg. Dont now how reliable those are and I have no spares possibilities if the issue is not the individual components.

While I am messing with this - going to change at least the rear shocks and bags -
I'm only the second owner and have all the predecessor work records. What few there was an alternator and a couple minor items.
The original Dunlop bags survived 26 years - replace with the same or what for suggestions?
This vehicle does not go 4x4'ing - I have two other GMC sierra's for that purpose.
But, Cheers,

Two lights (usually access & standard) when starting is normal for a deflated system. Then ECU tries to rise but cannot. Hence after a bit you get four light fault.

Is the tank actually full ?
Once you get four lights the ECU needs reset & often faults clearing before it will rise.

1) get the tank full of air
2) get some schrader valves & fill the bags manually. Then check HS readings.

pw, interesting
No tank is empty -While I was originally waiting for the RSW "gear" to arrive - I had originally gone over and rebuilt the valve block, compressor and checked adjacent wiring etc.
Had originally expected the "system" to fire back up off bumpers / exit setting as it had always before.
And yes the two lights bit, compressor would cut in and then light stabilizes on normal running height oh well
I will "jump" the compressor and fill tank and see about fittings to fill bags.
Can't mess up the feed lines - a couple are originally pretty tight.

I had originally expected, as convenient, to rebuild the compressor and replace at least the two rear bags and good to go.....
Oddly front bags don't seem very warn.

Will give it a shot and advise.

Cheers

Why not grease? You are dealing with logic level signals, not power. The grease will attract dust and dirt and end up impeding signals. Connections need to be clean, dry and corrosion free.
It sounds very like you may have got the solenoids crossed when you rebuilt the valve block, multiple sensor failure is very unlikely.

It's quite easy to do a manual override.

1. Get the tank full of air. Easy way is to bridge the compressor relay, which will engage the pump and the diaphragm valve. Best to have the engine running because the pump pulls 10A plus.
2. Unplug the main 12 pin connector at the front of the EAS housing.
3. Connect 12V to pins 12+13 & ground to pins 10+11
4. To raise the rear connect 12V to pin-5 (inlet valve), and to pin-1+2. This will energise the rear valves & open the inlet to allow tank air to fill the bags.
5. For the front bags, same as above but pins 3+4 & 5.

Once the car is up, reconnect & check height sensors.

Data.. The system went down and then I took the opportunity or was driven to rebuild compressor / valve block drawing on an assumption and the compressor was running to much sporadically.
And was very systematic in valve rebuild progressing one by one. I didnt take the example of some online "how to's" and tore it apart into components and reassemble.

Pw, had to do a cut and paste on that one.
Jumping the compressor relay is how I tested the rebuilt compressor.
Will take a look at and see what I need to grab for "contacts / gear"

From your "step by step"
#3 - leave those connected? - those are base pwr channel I assume?
And then
#4 & #5 can be contacted individually?

Thought I would ask rather than "lets poke here and see what that does"

Will see what happens and advise
Cheers,