I was trying to isolate the failed wiper problem on my 1993 300E 2.8 (4-dr sedan) but now I have a bigger problem -- it won't start! I'd appreciate all the help very much in isolating this one...
This evening I opened the relay box behind the fuse box and removed a few relays and put them back on after taking some notes on part numbers on them. I also replaced some fuses in the fuse box w/ new ones (even though the old ones looked ok, just in case). I did this w/o disconnecting the battery.
Soon after this, the car wouldn't start. It cranks as if it is going to start but no start. Battery is new, replaced just a couple of months ago. Any case, I also tried starting w/ a charged 12v jump-start power supply. Still no start.
Thinking that what i removed might not have been put back properly, I removed those same relays and made sure they are in properly. Also, the ones I removed could ony be put back one way as they will not fit if I accidently tried to put incorrectly. This is driving me crazy that I can't even take a relay out and put it back w/o a problem. I need all the help.
Here are the relays I removed and put back:
126 820 20 26 (green and says 601 646 12V ) has pins: 85, 86, 30, 87a, 87
001 542 68 19 (black and says 40A 12V) has pins: 85, 30, 87, 86
201 821 00 47 (black and a bit long w/ 12 pins) -- my guess this is the combination relay?
126 542 01 32 (black - long made by Hella and has a lot of wires also at the bottom) I did not take this out completely. Just lifted it up until the pins were out and put it right back in) -- my guess this is the Lamp control unit?
Anyway, those were the four units I removed and then put back as they were. What might have gone wrong? How can I solve this? Need all your help and would appreciate it very much.
Thanks in advance.
(If anyone want to know about the wiper problem, I will post it.)
It sounds to me like your fuel pump relay "left the building." I don't know if that part is located in the fuse/relay box on a 1993 though. On an 88 it's located behind the battery (with the OVP relay and the a/c compressor control relay).
BTW, the terminal numbers that you mention are function "standards"
30 = battery voltage to the relay contacts
85/86 are relay coil power and ground
87 = voltage out when relay is energized
87a is voltage out when relay is de-energized
Thanks for your quick reply. There are 3 more relays behind the ones I mentioned but I did not take them out. I couldn't take a look at the part numbers as they were all the way in the back. One is silver in color and the other two looked white plastic color. These are small square ones (about the same size as the green one I mentioned). So altogether there are 7 relays in my relay box behind the fuse box.
I will take a look at behind the battery area to see any relays there. But I did not do anything there at all. Can you tell me what the fuel pump relay look like and if there is a way to identify it by looking at it? And the OVP relay?
Electrical - Control Module
Part: 126 820 20 26 - Have no idea what it does
Relay
001 542 68 19 - This one has a fuse on top. Make sure its not blown. Have no idea what it does
Wiper control module
201 821 00 47 - Self explanatory I guess
Lighting control relay
126 542 01 32
Go back to the relays and pull them again. When you put them back make sure they are seated properly especially the top two above, oh and check your fuses to see if any of them blew. You did disconnect the battery before unplugging these relays right ?
Yes I am going to the car soon to take the relays out again and make sure they go in properly (I did this yesterday but want to do it again just in case...).
I never disconnected the battery before I took the relays out ....I should have (what was I thinking, disconnecting electrical components with battery connected..). You think it has something to do with it..Hope I didn't fry something
001 542 68 19 didn't have a fuse on top though (black)
You didn't fry anything by unplugging the relays with the battery connected. At least with the doors closed and the ignition off. None of the relays are powered at that time.
Checking fuses is a good idea but i can't think of a fuse that would prevent starting.
The easiet way to check for spark is to disconnect one of the spark plug wires, grab a spare spark plug, hook the wire up to the spare plug, and lay the plug on an exhaust manifold making sure that the plug metal body is touching the manifold. Have someone crank the engine and watch for a spark. You may be able to hear the slight *pop* *pop* as the plug arcs.
There are 3 relays behind the battery shield on an 88. The OVP which has the clear lid on top with a fuse visible, the a/c compressor control relay which has "Klima" or "Kompressor" some such thing written there. The remaining one is the fuel pump relay. The compresor and fuel pump relays are rectangular and have about 8 pins each.
These 3 relays are really much, much more than simple relays. Each one contains integrated circuits, diodes, resistors, capacitors, and who know what else. I believe that the compressor relay provides overspeed protection, killing the a/c compressor if you over rev the engine.
My wife's 88 260 was runngin great when she parked it at work a couple of months ago. She went to leave and it wouldn't start. I was about to replace the fuel pump assembly in a parking lot when I 1) swapped in a spare EFI ECU, 2) swapped in a spare OVP relay, and 3) swapped in a spare fuel pump relay. No change with 1 or 2 but #3 did it and she fired right up. What would kill a fuel pump relay like that? No idea.
Ok I went back to the car and this time I removed all the relays in the relay box (behind the fuse box) and made double sure they are plugged in properly (just to be safe, I removed the battery ground first). The fuses all seem ok too.
Afterwards, when I cranked it up, it felt like it was going to start, but still no start.
Spoke to the dealer about the Fuel Pump Relay and he gave me
part number 001 542 96 19 and it was abount $30. Asked him where it is located, he said the fuse box (and not behind the battery area)
I'm now confused because none of the relays in the relay box behind the fuse box has such a part number. Also looking at a pic of 001 542 96 19 on one of the parts sites, it has a fuse on it. None of the relays in the relay box has a visible fuse. So where is this fuel pump relay 001 542 96 19 located? My car is a 1993 300E 2.8 4-DR sedan. Any suggestions for places to look?
I briefly looked behind the battery area (behind the plastic cover) and saw couple of relays. One looked like the OVP relay w/ a 15A fuse on top (kind of tall slim rectangular one white color) based on the pics I have seen of OVP relay.
There was another Black relay 003 545 56 05 which seem to be the a/c compressor relay (based on an item on e-bay w/ the same part#). So where is fuel pump relay 001 542 96 19 ? I am going back to the car again...
It should be opposite the OVP & Klima/Climate Control relay.......
A simple way to troubleshoot the Fuel Pump Relay:
1. Remove Relay
2. Then short TERMINAL 87 & 15 using a jumper wire, about 2 inches.
If your car starts, replace relay asap. Good luck......
augapfel, yes I found the Fuel Pump Relay behind the battery area (along w/ the a/c compressor relay and OVP relay as you had mentioned.
This is the update...
So I took the Fuel Pump Relay and the A/C Compressor Relay out and did a visual and re-inserted just to clear any connection issue.
I also removed the wire connectors from both washer pumps. I decided to do this because, the windshield washer had stopped squirting a few weeks ago and also the headlight wipers haven't been working for a long time. So just to clear any shorting possibilities, I removed the wire connectors from both washer pumps.
This time I didn't bother to even open the fuse box. After connecting back the battery ground I tried starting. This time I was able to get it started after holding the ignition for a while and giving it a little gas...obviously I am very happy it started!
I drove it around for a while (no issues at all -- it drove very well) also taking care of some business w/o stopping the engine until I was back. Finally, after turing it off, I was able to start it back up normal. The problem seems to have disappeared but I can't tell what caused it in the first place. Don't know if this is a warning before some component failure?
This is a major detour I took trying to diagnose my windshield wipers which quit working and the windshield washer squirting which quit working just before the wipers!
It seems they all come in bunches...I really love this car otherwise. It runs very well specially on the highways as it speeds up.
I want to thank all of you for the help. I wish I knew what caused the problem. Any opinion? I will try again to isolate the wiper problem after a little breather....
Linear Mode
