ABC Light on dash
 

The ABC light, lights up on the dash while driving, soon the suspension will rise all the way up until you turn the key off then it will go all the way down,, any ideas of fixing this issue

Welcome to the forum.

Read through the ABC troubleshooting guide to get acquainted with the system. ABC has many components to look after.

Is this a new purchase for you?

Good Luck,

Bob

I'll second mercy-me, Welcome to the Forum!!! I've been in here a year and this is the place to be.


Moretech

sounds like your valve block orings are bad and fluid is leaking past them filling up the struts when the car is on and the system is pressurized and the fluid is leaking back past the orings and letting the fluid out of the struts when the system is no longer under pressure.

If you're going to DIY on a merc you really need to purchase a STAR tool. It is the diagnostic tool the dealer uses and allows you to see exactly why the ABC warning in the dash showed up.

If it is the ABC blocks, you can either have them rebuilt (jnash on this site rebuilds them), rebuild them yourself, or fork out $$$$$ to replace them.

There's another problem. Leaking valve blocks won't cause an ABC warning message. That's a distinct fault caused by low pressure or one of many other faults. Only way to find out is to read the fault codes.

In the meantime, make sure the ABC fluid reservoir is full. If its empty, don't even start the engine.

If you have some time, read the ABC thread below.

Nick

This is not true. If the ABC system senses that fluid is leaking by & causing the car to rise it will put a blue ABC visit workshop message in the dash. If it senses that the car has gotten too low due to leaking in the valve block a red ABC warning will show in the dash.

My SL is having this exact problem with the front left & both warnings have appeared in the dash. When you check it with STAR it shows only those 2 faults & no others.

ABC is clever and complex, but strangely it can't detect leaks or low fluid, just the consequences of them. It does monitor fluid pressure and temperature, plus the status of all the sensors and actuators, so there's a LOT of possible fault codes.

A mild valve block leak will only be detected by low suspension level at start-up, but it will normally clear when you start the engine and either put it in gear or raise the suspension level. This is quite common, and is more of a nuisance.

Re-sealing the valve block isn't a big deal. If the fault doesn't go away, its more serious, and needs proper diagnostics.

Nick

the only way the car will rise when it is not suppose to is if the valve blocks are malfunctioning. The car can detect when the valve blocks should be closed, but that the car is continuing to rise. This condition occurs when the car is not in motion. If the car raises high enough out of range the car will reopen the valve block to quickly make that corner sit correctly or if you you simply start driving the car will also start opening/closing the valve block as road conditions see fit.

The car can in fact detect a mild block leak while the car is running as long as it is not in motion and this can cause an ABC light in the dash. A low suspension level at start up is not the only condition that can cause a warning light caused by a leaking valve.

The car raising on its own when it is not suppose to has nothing to do with the fluid pressure or level of the fluid in the car. The only condition that can cause the car to raise is if the absorber is filing with fluid and the only way the absorber can fill with fluid is through the valve block. Now fluid could escape the absorber both through the valve block or through a leak and there's no way the system can know which one is causing the problem.

As an example, my car has a valve leak on the front left for both filling up when it is not suppose to when the car is running and not in motion (causing that corner to rise when it is not suppose to) as well as it getting too low after it sits. The codes for these are C1531-001 and C1525-001. One of these will cause a blue ABC light and the other a Red ABC light. If need be I can record a video of this occurring, the ABC light showing up right after and then a screen shot of the trouble code that STAR registers to prove that this is in fact how this all works.

Again, the system can deduct a leaking valve block if it is causing the car to rise when it shouldn't. Just sit and idle the car for a few minutes and watch the car slowly rise and then suddenly drop back to the correct level. This will cause the blue ABC light and the fault code telling you that you have a valve block problem. The workshop instruction manual just tells you to flush the fluid and put in a new filter, but if the orings are shot that is not going to do anything and you will need to rebuild or replace the valve block. The workshop manual is just hoping that merely dirty fluid is causing the problem when in reality this isn't the case very often.

Got a question for you. I flushed my 2003 r230 and replaced the filter. Car was fine, but it was 13 years old so I thought it might be time to do it. Within 2 weeks after the flush the rear end started sagging. I replaced the rear valve and it was fine again. Within another month the pump leaked so I replaced that. After that replacement the blue "ABC visit workshop" message started coming on within the first 1-2 minutes, either stationary or moving. Based on other posts I replaced the tow big accumulators and the pulsation dampner. Once again the same message still persists. I have taken the pressure sensing valve out and inspected it, but see no evidence of anything not working. Car sits at normal height, raises and lowers properly and doesn't leak anywhere. If I reverse engineer it the problem started after I replaced the pump. I took the car to MB dealer and had them run a diagnostic. They said everything checked out fine. Reset malfunctions, BUT still got the message. Any thoughts on what could be causing this. I'm thinking that when I disconnected the electrical connector going to the pump, maybe I damaged the connection somehow? Wouldn't that show-up on the diagnostic. Any help/advice would be appreciated.

check your hoses for leaks, particularity the hose that goes from the pump to the pulsation dampener. There are also two hoses that run under the front radiator that goes to the 2 front struts. I too had the same blue message and it was b/c of low pressure caused by these hoses weeping. They will start to leak/weep on the rubber portion next to the the metal crimp on the ends.

the hose that goes from pump to pulsation dampener goes through the engine compartment and is heat wrapped.

CHECKED THEM ALL AND NO WEEPING. This is driving me a little nuts.

Is your fluid level dropping? (if not, there probably isn't a leak to look for ...)

I did not see where you mentioned what the "stored" (or stored and current) fault codes were when the dealer ran the diagnostics. That info would likely prove useful.

Chris

I had the same problem. This article was a Godsend. https://www.youcanic.com/wiki/merced...nsion-problems

ABC light, need help
 

I’ve owned this sl500 for 4 months. After I purchased it, when I would hit bumps or go over dips in the road the ABC light would ding and flash on for a few seconds. Today I was sitting still at a parking lot and it sounded like a hose or something burst and the ABC light came on and will not go off. The ride home was rough, I think the ABC is damaged. Guess I’ll get it to the dealership. Any advice or help is appreciated. Also the car will not rise or lower.

I would guess one or more accumulators has gone south. Accumulators absorb the pressure increases from bumps. When they fail, the rubber hoses must step up and try to absorb the hydraulic pressure increases. They don’t handle that too well, and blow apart.

Make sure you dont start the car, you may run the ABC pump dry and hydraulic pumps aren’t fond of that, especially this pump.

If you can't or don't want to work on it yourself, find a good independent that specializes in Mercedes and knows the ABC system.

Check your ABC fluid level. If it is dry and you have a blown line it is best to have it towed so that you don't ruin the pump. If ABC loses pressure, it will lock in position as a limp home mode.

Your original issue was probably a bad accumulator (or two) and that also need to be addressed.