Location: washington d.c. area-falls church, virginia
Posts: 22
Very helpful V12 diagnostics tips. Thank You. I own a 1993 600SEL and have encountered similar issues. Current challenge I have is ASR and ABS lights. I have new battery, new alternator, new ground cables and extra ground cable at the battery. All trying to find out why the ASR & ABS lights intermittently come on. Brake pads are 6 months old and all with new pad sensors, properly installed. Front wheel speed sensors checked and cleaned. All ASR and ABS connections checked. No codes present in ASR / ABS module. Only present code that will not go away is a right 02 sensor heater inop, with new Bosch 02 sensors only 3 months old. I may have to check the wiring for the 02sensors. Engine wiring harness seems ok and EAs work ok and Mass Air Flows recently cleaned.
Any ideas?
The problem is typically with the front ABS sensor wiring (intermittent signal). This coaxial wire has to turn with the wheel and flexes with the suspension travel. For LHD cars, the right wheel sensor gets the majority of abuse, due to potholes, curbs & etc.
As soon as there is lack of signal from any one wheel sensor, both the ASR & ABS light will light.
The typical one that goes is the right wheel sensor for LHD cars.
Vehicle: SEC 600 COUPE (RHD) One of the chosen few.
Location: Leicester UK
Posts: 1,358
First check to see all your tyres are the same size..
then check the rotation on each wheel seperatly.. that is with ignition on and rotate each wheel and see the ligt comes on after half a turn..
then the steering sensor..
jack the front up and turn left to right..then right to left....
then..there are gearbox issues that will affect the asr and abs lights ..
you need to try to pull the codes for the gearbox....
__________________
If you've GOT to have a extension,
Have a BIG one.
Bob B. contacted me with an interesting modification that he made to his pump. After removing the pump’s cover to make the shut-off pressure adjustment to his Bosch pump, he actually cut a flap in the side of the pump cover right where the shut-off switch is located. Now future adjustments can be made without needing to disconnect all the air lines. Not a bad idea. And by the way, reducing the shut-off pressure has completely restored operation to his closing assist system. Here’s a picture of his handiwork. Note that this may be practical only for the Bosch closing assist pump. I’m not as familiar with the Hella pump.
I'm new to this forum.Just joint.I had own a 280 SE 126 for close to seven years now, imported used from England. Done about 350K km myself plus 220K km by the previous owner.Since that car is real nice, I would like to have another Merc. S320 W140 model year 1994 or 1995. I can't afford a brand new one.In my country - Malaysia, Road tax for anything bigger than 3.5 liter is too high for me. This s320 and 280 is going cheap because not many willing to fork out so much to pay for the road tax and maintenance. Any advise ?
Very helpful V12 diagnostics tips. Thank You. I own a 1993 600SEL and have encountered similar issues. Current challenge I have is ASR and ABS lights. I have new battery, new alternator, new ground cables and extra ground cable at the battery. All trying to find out why the ASR & ABS lights intermittently come on. Brake pads are 6 months old and all with new pad sensors, properly installed. Front wheel speed sensors checked and cleaned. All ASR and ABS connections checked. No codes present in ASR / ABS module. Only present code that will not go away is a right 02 sensor heater inop, with new Bosch 02 sensors only 3 months old. I may have to check the wiring for the 02sensors. Engine wiring harness seems ok and EAs work ok and Mass Air Flows recently cleaned.
Any ideas?
Thanks again.
Bill Mercer
You are guys so helpfull for newbies like me.
1994-500S
I have a similer problem like Bill, but with a clear signs i guess. My speed indicator
not reading steadly .. like shaking betwen 80 and 90 for example. ASR/ABS lights up soon after.Moreover, I can clearly hear a rubbing noise coming out of the front left wheel.
I removed the front wheels speed sensors and found so dirty(speicaly left side), clean it and the noise disapper , pointer and ASR/ABS were all fine for few weeks . Then it all came back again now ... remove them found clean , clean it again but still the same problem .. any Ideas ?
It’s about a 15 minute job to change your fuel filter once you have your car lifted. My car is a 1997 model S600. Most other W140’s are probably very similar if not identical. I have a low-rise lift making the job really easy, but putting the rear up on ramps should be enough. Do not work under your car until you have it safely lifted (ramps, jack stands, or lift). Do not work with only a jack supporting the car! You need to crawl all the way underneath the rear to access the fuel filter.
The fuel filter is located under and just aft of the rear passenger seat. It is concealed along with the fuel pump under a protective plastic cover. This pic shows the cover and the location of the three nuts that you must remove to remove the cover. Simply remove the nuts and work the cover off of the studs.
The fuel filter and fuel pump are clamped into a bracket together, and the bracket is suspended from the bottom of the car using rubber grommets. Check the condition of the grommets. If they are in bad shape, replace them. You may need to release the bracket from the grommets to make access easier.
First, clamp off the fuel lines on either side of the filter. Loosen the screw that holds the filter in the bracket, and loosen the hose clamps holding the fuel lines on the filter. Before you remove the filter, note the direction of fuel flow indicated by the arrow on the filter. Be sure to install the new filter with the arrow pointing in the same direction. Have a drain pan ready, and pull the lines off the old filter. About 1-2 cups of fuel will spill out. Remove the old filter, and put the new one in place (arrow in the proper direction). Put the fuel lines on the new filter, and tighten the hose clamps. If the clamps are in bad shape, replace them. You definitely don‘t want a fuel line popping off. Tighten the screw to clamp the filter in place. Replace the cover and tighten the nuts holding it in place. That’s it.
This write-up documents changing the plugs in my car, a 1997 S600. 1995 and earlier model years with distributor ignition will not have the ignition coils shown in the pics at each cylinder. Changing the spark plugs in the V12 is pretty straightforward except for cylinder #12, which is buried under the tray for the wiring harnesses. It took me about 45 min to do #12 and another 1 hr to do the other 11.
If you’re more creative than I was with flexible extensions and socket universal joints, you may be able to reach #12 without flipping up the wiring harness tray as I am about to describe. #12 is under the tray as shown in this pic. # 6 is also partially blocked, but you can reach it with two shorter extensions and a U-joint.
Begin by removing the climate control intake plenum (same thing you would do to change the pollen filter). First, disconnect the vacuum line to the flap on the passenger side, and then remove 6 screws shown in the pic.
Under the driver’s side of the plenum, twist and release the climate control’s air temp sensor.
And, finally disconnect the electrical connector for the wires to the smog sensor, and lift the intake plenum out of the car.
Now, from the driver’s side flip up the wiring harness tray that is behind the firewall. It is hinged and easily lifts up. Remove the three 8 mm hex screws holding the forward harness tray (the one above #12) in place.
Lift the tray, and you’ll see that you now have easy access to #12. The tray is split in the middle so you can just lift this side of it enough without having to undo the entire tray all the way across the engine compartment.
Change out #12, put the tray back in place, and reinstall the climate control plenum. Then move on to the other 11 plugs.
Changing each plug, requires removal of the ignition coil. To do this, disconnect the coil’s electrical connector, unclip the metal clip that holds the coil, and grasp the coil by the top and wiggle it out of the spark plug tube. You then need to remove the coil’s retaining clip. Just squeeze the open end of the clip, and work it off of the intake manifold. You’ll see.
Here’s the removal of the ignition coil.
I used an air duster can to blow any junk out of the spark plug tube. An air compressor hose would be better. The ignition coils have rubber gaskets to prevent stuff from falling into the tube, but better to be sure. You don’t want any grit falling into the cylinder.
Using a spark plug socket on the end of a long extension, remove the old plug and install the new one. Torque the new spark plug to the appropriate value. My owner’s manual said 20-30 Nm. Replace the coil retaining clip and the ignition coil, and reconnect the electrical connector.
After 8 are done, it’s kind of annoying to think that the V8 guys are kicking back enjoying a beer by now. Hang in there. I know your back is killing you. Only 4 more to go. When you’re done, check your work. I actually left a coil unconnected and didn’t find it until I had started the car and experienced a shaking engine from the misfire. Re-checking revealed the disconnected coil.
k. Another failure mode of the Bosch pressure shut-off switch. Guide fins breaking off of the white plunger.
Thanks to Simon C. for describing another failure of the Bosch pressure switch. Simon’s pump was timing out regularly. Upon closely watching the white plunger of the shut-off switch, he noticed (like Posix did in section e) that the plunger wasn’t moving at all. He tried pulling the plunger with needle-nose pliers, but it still would not move, so he resorted to disassembling the pressure shut-off diaphragm. The culprit turned out to be broken fins on the white plunger. The plunger has several tiny fins around its perimeter, which guide the plunger by mating to slots in the black housing. A couple of these fins had broken off and jammed the plunger. In his case, the rubber diaphragm inside the cylinder was fine. Simon simply removed the plunger and cleaned out the debris. Upon reassembly and adjustment of the shut-off pressure, his pump was back to normal operation. As he describes, the shut-off switch diaphragm can be separated into two parts and repaired without desoldering the electrical part of the switch from the circuit board. First, remove only one screw holding the rear section of the black plastic housing to the circuit board.
Second, release all the small clips around the circumference of the black housing to separate the rear of the diaphragm, leaving the section encasing the white plunger connected to the circuit board. You can now remove the white plunger and the rubber diaphragm to inspect them for damage.
Last edited by Brett San Diego : 12-04-2006 at 01:01 AM.
. Then it all came back again now 
... remove them found clean , clean it again but still the same problem .. any Ideas ?
Linear Mode
