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ADS 1 System Problems, 013 HHTwin code

532 Views 8 Replies 4 Participants Last post by  Chris Morlock
So I have been trying to get the ADS 1 system on my 1995 sl600 back up and running again. It's been an odyssey to say the least.

When I purchased the car 6 months ago it was stuck in the tallest position with the ADS warning light on. It was very firm ride but has zero leaks anywhere and held perfect pressure even after months of being in the raised position without leaking a drop.

I scanned codes with HHTwin and got a Y53 and Y54 code plus an 013 They read exactly like this:

008 Solenoid valves RA Y53y1, Y54y1
009 Solenoid valves RA Y53y2, Y54y2
013 Supply pressure too low

I first thought about the accumulators (balls) being bad because that's what you see discussed on the forums mostly, so I purchased 4 Cortecos. I decided to change the rears out first and proceeded to find the old ones in great shape, not collapsed, and actuall Coretcos which probably had been replaced in the last couple of years. So I sent that $400 adventure back for a refund and just kept the old balls in place.

Then I decided to change out the rear valves Y53 and Y54. Ordered a used set and installed them, no change- same codes. It baffled me for a bit so I tried to trace the wires, and sure enough some idiot had disconnected one of the valve's connectors in the spare wheel well. I wish I had checked this prior to parting with another $300 for the replacement valves.

As soon as the connector was put back the Y53 and Y54 codes disappeared, and the system in HHTwin can no go into the "zero" position, meaning the three modes shown in HHTwin as comfort/O/sport. Before it was stuck in sport, now it seems to be stuck in O. I can use HHTwin to put the system into comfort mode, and the ADS warning light extinguishes immediately when I do this.

As soon as I dissconnect HHTwin the ADS warning light goes on again and baclk to square 1. The only code is the "013 Supply pressure too low".

Looked high and low to find another person with this 013 code and there is nada anywhere. I know the diagnostic trouble shooting manual STAR TekInfo
with no real lick considering all of these procedures usually has specific codes in either HHTwin or the impulse codes. I can't even find a corresponding impulse code to the "low pressure" code in HHTwin.

Really getting confused here, what's the deal? Pressure in the system seems good, and the spheres are all good, and it rides a bit better in the "zero" position. The ADS button on the dash doesn't realty do anything. Ride height is all at the tallest setting all the time but even.

My next target area would be the distribution block and of course the pump. If there is "low pressure" could this be related to the distribution block? I guess I could pull the front spheres and make sure they are still good as well.

Thanks for any help or ideas, this has been a very challenging project. If anyone has any questions I am glad to respond, I learned a lot about the system.
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All the codes have been cleared except for the 013 Supply pressure too low, which immediately pops up as soon as you leave the HHTwin. I think I am looking at the valve block and the pump, debating which to do first.
Pazo, you are a genius! Now things are starting to make sense: I was thinking the exact same thing. I've been through this system from head to toe and could not figure out how the N51 computer was even reading any pressure to begin with. There are zero sensors so I was getting crazy thinking maybe it had some kind of logic connected to the damping valves or something it was looking at in terms of the flow, but this was getting pretty silly technically. Except for the valve block, there is no real "logic" in this system other than the hydraulic-mechanical which either works or doesn't, so the valve block was looking like the most "logical" issue.

Considering it develops enough pressure to raise the system to the highest level, leaks nothing, and never goes "down" or drops at all (even after being parked for weeks) I couldn't understand the "pressure" issue in the code in HHTwin.

Well, here is the answer, Pazo was right: the actual impulse code DTC list says #13 code is the oil level switch (or a computer issue). I was confused because the difference in terms with the HHTwin, it's "013 Supply pressure too low". Pressure clearly was the wrong word, or at least super confusing! I included the diagnostic procedure, will report back if this works!

Thanks again Pazo.

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Viola, it works with a jumper wire, light is out and the suspension is now in comfort mode at the middle height, awesome. I can't believe I spent so much time and money on basically what amounted to 2 problems:

1) One of the rear dampening valves connectors was not connected (dangling, positioned behind a plastic shield in the spare tire well)
2) The level sender "S44" which is very similar to the coolant level sender, a sealed unit

Looks like the sender is available and cheap, thank god, widely available at around $30 (part #011-542-05-17) Even the reservoir (part #1293200514 is only about $85.

Literally could have fixed this with some patience and electrical diagnostics but instead went crazy replacing parts and draining the system and trying to bleed it at 6 different points, hilarious. Just goes to show that a decent electrical check could save you tons of work.

Thanks again Pazo!

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Thank you all, this issue was completely resolved and the system works great. Unfortunately my transmission went down, lol, so now I am back to the drawing board getting ready to rebuild it myself.

Here is my new sensor, it's part number #A 011 542 05 17. Was going to also try and fix the original so in the future I will have a spare, will post the process here. The part new was about $35.

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