1998 SLK 230 Electrical problems....help - PeachParts Mercedes-Benz Forum

reverendcolin · #1 06-08-2007, 02:28 PM

I picked up a 98 SLK230 last year and it's been great. A couple small problem like a few dash lights out and the alarm seemed to be intermitten.

It's got 42K on it and hasn't seen a winter to the best of my knowledge.

Yesterday I decided to take it to work. I jumped in and got to the end of the drive way and turned the windshield washers on...but they didn't work. Nor did the wipers, turn signals, power windows, locks, and I find out the top isn't working either.

I've checked all the fuses and the grounds and find all seems well. I popped the top of the control box to see if anything was loose but all seemed to be find.

I've got a CD with the wiring diagrams but I seem to be overlooking something.

Could it be the control box unit itself? Am I missing somne relays?

Thanks in advance.

mbdoc · #2 06-08-2007, 03:01 PM

The combination control module controls ALL of those listed functions.

It gets power from Maxi fuses #1 & 2

reverendcolin · #3 06-09-2007, 03:37 AM

Thanks for the info.

This would be the M1 and M2 in the fuse box at the left rear of the engine compartment?

I'll recheck the fuses this morning. They looked good and tested good so I'll check the wiring... maybe a loose connection.

BTW, the windshield washers did work, It was the wipers that didn't.

Thanks again,
Colin

reverendcolin · #4 06-10-2007, 05:12 AM

All the fuses are fine. There's power through all the fuses.

The four terminals at the rear left fuse box (eng. compartment)all have power to them (2 all the time) the other two with ignition on.

I followed the wiring harness to the right side under hood to the box that holds the control box, and whatever else is in there. There;s 4 or 5 fuses there and they are fine too.

All the wires seemed to be plugged into three (3) large modules which look like ECU's.

Are there breakers or modules in these boxes that can be checked?

Thanks
Colin

reverendcolin · #5 06-12-2007, 01:29 PM

Hello, anyone out there.....is this mic on?

reverendcolin · #6 06-13-2007, 12:36 PM

Maybe this will help someone else. The problem was the PSE unit. corrosion on the terminals. I found some great info else where on how to remove and repair the unit.

I have a feeling this one won't be repairable so..does anyone know a reasonable dealer or re builder for these items?

Thanks Reverend Colin

nhdoc · #7 06-13-2007, 01:38 PM

Do you know if the part needs to be "coded" to the particular car's VIN? Some of them do and if so then you'll need to have the dealer install it most likely. If not you can try calling Duval motors in Gainsville Florida and see if Steve can get you the part - their prices are about as low as anyones I have found.

reverendcolin · #8 06-24-2007, 01:18 PM

The PSE has to be the right one but it's not coded, just a drop in type thing.

I installed the new unit and everything worked.....then it didn't work.

I disconnected the battery...waited...reconnected...and it worked.....later when I tried, it wasn't working again.

Is there a relay some where in power line to the PSE?

Something I'm missing?

If this was a Harley or a Hot Rod this would be a piece of cake.

I find the electrical system to be so over engineered as to be dangerous (to my mental health), a few breakers could have done they same thing as the circuit board. Who's idea was it to put it there and with the circuit board on the bottom?

I'm not real happy with Mercedes at the moment.

sined · #9 09-04-2007, 06:08 PM

if someone can help.

slk230 1999 , the interior lamp stay on even with all door shut, both front windows won't go down,the s98 roof swith never light, the roof doens't move either, the door won't look when riding. only the passenger light will blink when remotly lock or unluck the door.

I took a look at the PSE in the trunk, yes I found some ( just a little ) corosion on some pins, I clean and all my problem are still there. I took a look at most ground that didn't change any status either.

any ideas,

thanks

reverendcolin · #10 09-05-2007, 03:09 AM

I got a lot more help at Benz world than I di here. Seems to be mechancical minded group. Check this thread and it may help.
http://www.benzworld.org/forums/r170-slk-class/1323845-1998-slk-230-electrical-problems.html
My problem was the PSE box and I replaced it. I took it apart and cleaned it a couple times and it worked for a bit and crapped out again.

If after installing the new unit I had the problem of it not working after I turned the ignition off. I installed a battery cut off like this:

But even before that make sure you have a surge surpressor between your battery and the postive.

The problems I had after installing the PSE was...it was fine as long as I had the car running. As soon as I turned it off, I'd have to unhood the battery, wait a minute or so and reconnect it. Then it would work fine till I stopped again.

How did I fix this????
One night I came out to go to work and when I opened the door the courstey light was working....it's been fine ever since.

Don't expect a lot of help from these boards. Not that they don't want to help....but ....It's that if it isn't in any manual or book they don't know.

I've learned a lot about Mercedes Machanics in the last several months. They're about the same as the new breed of Harley mechanics.. Book smart.

If I can be of any other help please E-mail me.
Rev. Colin

TimFreeh · #11 09-05-2007, 09:01 AM

I'm a bit confused... Lets review the sequence of events.

1) you have an electrical problem, and you describe the symptoms
2) MB DOC points out that all the items that are malfunctioning are controlled by the combination control module. You check what you think are the fuses to the control unit and they appear to be OK - so I guess you conclude that the module is OK.
3) But your problem persists so...you head over to BenzWhirled for more advise and opinions.
4) People over there tell you the problem is in the "PSE unit" - first they postulate that corrosion on the terminals is the problem. I'm not sure if the "PSE unit" unit is the same thing as the "combination control module". Is it?
5) You find the PSE unit and clean the terminals - problem still exists
6) You replace the PSE module (at a cost of $390) - problem still exists
7) You return here and inform the Mercedsshop community that "you got a lot more help at BenzWhilred then you did here" and "they seem to be a mechanically minded group"....
8) You then state that "you had a problem of "it not working after I turned the ignition off".. and your "fix" to this problem is to install a master battery knife-blade cutoff switch? How did "it" work when the power was disconnected?
9) You finally managed to fix your problem by opening the door on your way to work...

You then tell people to not expect much help from these boards and that Mercedes "Machanics" are book smart and you imply that they don't really know what they are doing. You also offer to help via E-mail if anyone has any future problems with the electrical system on their SLK's.

I guess I missed the part where you actually brought your car to a Mercedes Mechanic (dealer or independent?) that had the proper tools to troubleshoot this problem?