A few weeks ago, I picked up a fairly decent 2003 ML350 for $1500, and I'm in the process of curing it's woes and ailments. When I bought it almost all the warning lights were on, and now I'm down to three warning lights.

After buying an iCarsoft MB II, and replacing a few items, the lights I'm left with are SRS (there is something wrong with the passenger's front seat, one day I'll trace the problem), and an intermittent oil level warning light, one minute it is 2 liters low, the next minute the oil is high. The sensor is bad, I can probably replace it, but I'm just going to pay an independent MB specialist shop to do it.

The last and most puzzling light is the BAS/ESP warning light. Today I was in a junkyard, and scored a few good parts off a 2000 ML500 (like the pre fiber optic bose amp, because I'm replacing my MCS), and I picked up an ESP Module from right behind the fuse box, looks perfect, and worth $50 to take a chance. My iCarsoft scanner says that there is a CANBus communications failure with the ESP module in my ML350, so I assumed that my ESP module had died.

With a great deal of hope and enthusiasm, I unscrewed the cover behind the fuse box, to find that there is no ESP module, at all in my ML. Not even the connectors for the unit. Theres a slot for it, but no module.

So now I'm just confused and the only reason I can think that it would be turning on the ESP/BAS light is because the system has been mis-coded to believe it has an ESP module, when it doesn't. Also the MCS kept complaining about a problem with the TeleAid system, and there was never a phone system in this truck, and no navigation, and the CD changer in the back wasn't communicating across the DB2 fiber optic system, it was there, but the MCS didn't see it.

Naturally the iCarsoft MB II doesn't allow me to edit or recode the ML, is this something I'm going to have to find someone with an SDS and have done?

 

The ESP in that truck is in the ABS hydraulic unit/controller. All one piece.

 

Thanks, that would make sense.

I am confused however, that my ABS light is not on, if the unit is dead, wouldn't it light the ABS light as well as the BAS/ESP? The ABS bulb works, because it lights up just before starting.

 

Read the "C" codes in the ESP control module.

 

My Scanner will not connect to either the ESP or the BAS modules. It claims a communication error.

 

What about the ABS module? There has to be a body code somewhere.

 

I'll check to see if it can read the ABS module.

 

Okay, my iCarsoft MB II scanner, has two ways to read the modules, manual and automatic. In automatic it scans the system of all available modules and gives me access to them. In manual it lists all the modules and will either connect to them if they're there, or fail with a communication error.

In automatic mode, it sees the ESP system, but fails with a communication error when trying to read the codes.
In manual mode, it fails immediately when trying to communicate with the ESP module.
The same thing happens to BAS.

I don't have access to ABS (in manual or automatic).

 

Gentlemen, ABS, BAS & ESP codes are all stored in the ESP Cont. Module.

 

Then you just have a code reader and not a scanner. How much did this iCarsoft cost you?

 

It was about $150, it certainly isn't as comprehensive as SDS, but it does retrieve DTC codes and will clear the faults if the problem has been corrected. It can also handle the steering angle calibration, and read and display the data streams of any module it can communicate with. I think it would have no problems with the ESP/BAS if the module was working. I think the ABS light not being on, and the ABS working correctly is because it is a relatively dimwitted system. No higher math there, wheel locked->modulate. The iCarsoft MB II has been very handy on my SL55, and has no problems deep diving into any of its modules, but it doesn't allow me to edit any of the coding, or anything very sophisticated.

 

Are there any codes in any other module?

Is there any other component in the veh. that is not working?

Did you have or presently have a leak in the windshield washer reservoir?

With the key on, check both contacts at fuses 22 & 27 for 12v with a test light or DVOM.

 

Yes, the SRS module has several codes related to the passengers seat occupancy sensor. The Engine ECU had codes for the cam sensor until I replaced it. And the Transmission controller had codes because the fluid was low and it was slipping until I changed the fluid and filter.

As far as being unresponsive to the diagnostics, no, everything else responds to communication requests.

There is no evidence of a washer fluid reservoir leak, however the ABS unit seems pretty well coated in what I assume is power steering fluid, or maybe oil. The truck has 200000 miles on it, so everything under the hood is pretty grimy, it wasn't very well maintained. I do take your point however. Today I'll pull the reservoir, and clean the ABS unit off with shop rags, I'll pull the ABS connector and clean it with electrical contact spray, and check the harness for any broken wires, corrosion or other issues. However a visual inspection shows the harness leading to the ABS connection appears dry and undamaged.

All four test points on those two fuses show power with a test light, my volt meter bit the dust the other day, I need to pick up a new one.

 

Clean that eng.

My question was, Is there any other component in the veh. that is not working? Component, not module.

Strip the covering on the ESP module and check for broken or corroded wires.

Your leak is probably due to a faulty O-ring at the reservoir. Is it low on fluid or did you add fluid in the past?

Clear all codes in all modules. Then cheek for codes again and post them.

 

Definitely on the list. There is a slight valve cover gasket leak, maybe even an oil cooler/oil canister seal leak. I fixed all of these on my CLK55, and the ML350 shouldn't be any more difficult.

The other malfunctions are pretty limited.
A bad window regulator (driver's rear door)
Bouncing door lock (driver's rear door).
The passenger's front seat occupancy sensor is shorted internally causing my SRS light to stay on.
The transmission has been neglected, so I'm replacing the conductor plate, connector and doing a fluid and filter change. It probably doesn't need the conductor plate, but while I'm in there, I figure I might as well, since the truck has more than 200K. It helped my CLK55 a lot.
The steering wheel feels loose. Nothing else on the column moves, but the steering wheel can be moved along the X and Y axis about 1/16" I am guessing it is a bad bearing right behind where the steering wheel attaches to the shaft in the column, which probably can't be changed without changing the whole column, so I'll probably replace the whole column.
The instrument cluster is showing signs of impending failure. The Outside Temp and clock don't start displaying correctly until I've driven the truck about 20-30 minutes.
The oil level sensor is bad, one minute it is showing 2 Liters low, and then next it is showing Oil High. (Something I'll have my independent shop change)
The servo/motor for low range is stuck, apparently that's common because no one ever uses low range. I have the new one and I'll change it when doing the transmission fluid/filter change.
And the only other issue WAS, the MCS system. The head unit was dead, and the CDC along with it. I replaced the head unit with and aftermarket unit, and replaced the Bose fiber optic amp with a 2000 MY Bose non-fiber optic amp.
Everything else (except for the SOS/Teleaid system) works well.

I've resigned myself to replacing the entire ABS Pump and ESP/BAS module. (Well, I won't install it but I have an independent shop that is reasonable do it, and they have SDS in case it is needed.) It's expensive, considering I only gave $1500 for the truck, but like the SRS light, and the Oil Level light, I want all of the lights off.

I have only had possession of this truck for about two weeks. Neither the power steering fluid, nor the washer fluid have dropped enough to notice. But there has been some kind of leak for quite a while. I'm leaning toward the two oil cooler seals, and the oil filter housing seal. That side of the engine is pretty greasy.

As of last night the only module throwing any codes is the SRS module (and those codes can't be cleared until the problem is corrected), the ESP module still refuses to communicate, because I haven't had the time to clean the existing unit.

I did identify a couple of the rattles last night. The heat shield above the muffler in front of the rear axle has come free and is rattling against the exhaust, it looks like the mounting nuts have rusted to nothing. Also the driver's side exhaust manifold heat shield has rusted around it's bolts allowing it to flop around.

 

Wow, you bought one with a lot of issues.

 

I want an ML55, and one day I'll find the perfect one, but for the time being I needed to replace my 99 Land Rover Discovery Series II which was approaching 300K miles and was costing a small fortune to feed, and was getting costly to maintain. I needed an AWD highway vehicle that got better than 15 mpg and the ex-wife got the Outback in the divorce. As far as this ML350, it isn't in bad shape, the previous owner(s) just didn't maintain it very well. I have found that the people where I live, can't really afford to properly maintain a Benz and the nearest competent shop is a little over an hour away. My SL55 was sitting in a guy's garage, practically on the floor because the o-rings in the ABC block were shot, so 10 minutes after parking the hydraulics would bleed off. The car was flawless otherwise, but he phoned a dealership that quoted him over $12K for two pumps and 4 struts, which wouldn't have fixed it anyway. I bought the car for $10K, spent $100 on it and now I have a perfect 06 SL55 with only 82K miles on it.

Thanks to low cost replacement parts, and my willingness to turn wrenches, I'll end up with a decent, useable ML for around $3000, which is about what I was looking to spend in the first place. I don't expect to make money on any vehicle, I enjoy working on them and I don't have a problem with imperfections.