1992 500E LH Module - PeachParts Mercedes-Benz Forum

Bryan Harter · #1 02-06-2003, 02:30 PM

Does anyone know what the difference is between the 500E LH module and the 400E LH module ?

I suspected the problems I was having may have been related to the LH or EGas modules. It has been 11 months since the problem started. I replaced a bad cap and rotor, but still a slight miss, then it got worse, started surging. Especially bad when the weather was cold and/or damp. Replaced a couple sensors, timing chain (was overdue) and crank sensor....still nothing solved the problem, just made a minor (livable) improvement.

I had a SuperChip in my LH module, pulled that and went back to the OEM chip, darn thing would not start. Replaced the LH module with a 400E LH module running my OEM chip and the thing started and ran perfectly !!! No missing/no surging....

There is a part number difference of one digit in the xxx-xxx-XY-xxx position and they look different when you try to open them up. The 500E is nicely hinged, the 400E seems to be designed
to allow limited access to the eprom. The tipoff was there seemed to be something that caused the TBA to react when the LH module was wiggled around with the case open....possibly a bad solder joint on the board.

I need to investigate my options....but so far it looks like $2500 to get a new 500E LH module or run a free 400E module....at
opposite ends of the spectrum. I am going to investigate finding a wreck or possibly buying new from the fastlane....

I am curious what the differences may be, but I don't know if any of you out there have gone thru this....

Any sources for new / used modules would also be appreciated.

Thanks,

#2 02-06-2003, 04:46 PM

Bryan,

I'm confused. If the 500 chip in the 400 module runs perfectly, why would you spend money on a 500 module?

Randy
'94 E500

Bryan Harter · #3 02-06-2003, 05:05 PM

Randy,

I am not saying I want to spend the money...I am curious as to what the differences may be. Am I giving up anything using the 400E module? Could it cause any problems?
I don't know, my tech didn't either.

The single digit difference could account for the chip, but it was obvious the construction was different.

It is nice to know for all the other 500E owners if in a pinch the LH module goes out, a replacement is not limited to just the rare 500E parts...

Bottom line, it runs great so I will probably go this route for now.

need2speed · #4 02-06-2003, 05:39 PM

Hi Bryan: check out this thread: Superchip Problems.

Bryan Harter · #5 02-06-2003, 06:06 PM

Dean,

Thanks for the link! Very interesting.
That is essentially the same thing I encountered. Seems the Superchip "brainwashes" the LH module....I still think the problem was in the LH module as the new module accepted any and all chips and ran great.

I tried 3 chips, OEM, SuperChip and a RennTech. None worked in the old LH module after the SuperChip had lived there for 5 years. I proved the chips are fine, so now I guess I can try to contact SuperChips and find out what might cause the "failure to start" problem. I am curious as to what might cause the LH module to not recognize any other chips....the start parameters for any chip must be essentially the same.

If I understand your circumstances were similiar. The original LH module didn't work with anything but the Old SuperChip and the new SuperChip. You never solved the mystery of why the LH module refused to start the engine with another chip. I know that the LH module is "Adaptive" in that it will learn certain driving habits, so if you change chips, it will take some time to relearn how to react to certain requests you make.

I was told it will restrict power to the engine when it detects wheelspin, then adjust itself back to 100% power as the driver requests it and there is no detected slippage. If you stomp on the pedal and invoke the ASR, then backoff and do it again, the car will feel "down" on power. I believe my tech warned me that
the car would feel different for a while as it re-learned my driving habits after he had done some work to it a while back (I think it was a TBA replacement)

Did you ever swap the LH module with one from Benzmac ?
Was it an identical unit? I wonder if he has it for sale?
My parents are in Powder Springs, GA (Marrietta), I am looking
forward to a chance to visit MB Autowerks someday soon.

Thanks again for your help....now if we can just get RUN.EXE running....

Benzmac · #6 02-06-2003, 08:12 PM

I am pretty sure that the 400 and 500 LH controllers are the same except for the prom. I installed a 500 LH into a 400e after I reprogrammed the chip. It is running fine.

I don't know of a reason why the controller would not start after pulling out the Superchip.

It sounds like you had a problem with your 500 controller and it was worsened by taking out the chip and installing another. I don't know of ANY protections that can be invoked by a chip. I have done this 100's of times with no problem.

I would use the 400 controller with the 500 chip and let it roll.

need2speed · #7 02-06-2003, 08:25 PM

Bryan: One theory I have is that successive tune-ups optimized to the Superchip's non-stock fuel map customized the car to the chip (brainwashed as you say). I'm wondering if a different chip would also require a tune-up to work with it's different fuel parameters?

I didn't use Benzmac's module when I found out all I needed was a new chip. There are several sources for either salvaged or remanufactured modules from M119 motors (mostly SL500s). You can try Potomac German Auto.

Bryan Harter · #8 02-07-2003, 09:51 AM

Benzmac & Dean -

Thanks for your input....I am sure that functionally the LH modules seem to be pretty compatible even if they don't look
too similiar when you open them. It helps to know that some others have substituted the modules with successful results.

Have a great weekend.

Bryan

run.exe · #9 02-07-2003, 05:33 PM

I am MOST interested in trying this experiment on my 1993 500E; does anyone have a 400E LH module he/she is willing to let me try?

I will pay round-trip shipping, plus "a little something extra" for the trouble, if required...

RSVP / thank you,

Bryan Harter · #10 02-07-2003, 08:07 PM

I picked up The Beast from the dealer and have driven some 50 miles tonite....it is running great!
Scott - I hope this leads to a solution for you....

JimF · #11 02-09-2003, 12:00 PM

Being that this was my forte (for 42 yrs) before retirement, here some comments.

Bryan: If the chip does not work it looks as though that it was damaged OR the socket was damaged by the removal/insertion of other chips. If the socket or pcb was damaged, it can be repaired very easily by someone who has pcb experience.

Once the LH module is removed, the self-adaption (S/A) is reset nominal so plugging in a new chip will start it out 'fresh'. The chip cannot re-program the LH module so that it will not accept another chip.

The CHIP itself was most likely 'zapped' by static electricity rendering it useless or a TIP of the pin was bokern and/or folded under during insertion. It looks as though it was inserted but it's not!

These items can be repaired and the chip used again if done carefully. A pin can be resolded provided that there is enough portion to solder to. Do it all the time!

In my experience, it's the EPROM that sets the performance: I have tried three (3) different stock eproms in my S500 (M119.970) engine: 'E': 420, 500, 'S'; 420 and all work nicely. So if the 'proper' eprom is used in the LH module, it would be ok to use.

run.exe · #12 02-10-2003, 02:14 AM

Sooooo...

Is anyone willing to let me try his/her 400E LH module?

; )

Bryan Harter · #13 02-10-2003, 11:03 AM

Hi JimF,
It is interesting to have someone with background in this area, in summary, this is what I experienced:

The superchip works in the old LH module, but no other chip will work in the module. The other chips, OEM and RennTech work in the new LH module. I have not tried the superchip in the new module as I fear it might have the same effects....maybe it is bad and causes a problem in the LH module once inserted. The fact that someone else had this exact problem scares me and I am not willing to risk my new working LH module.

I don't know how the reset function works in the LH module
but it is pretty strange the car will not start with any chip in the old LH module except the SuperChip.

I inquired via email with SuperChips and their reply was they don't make a chip for this car....nice customer service....

I believe the LH module is damaged, it runs with the superchip, but refuses to "reset" after installing another chip. I runs very rough with occassional surging / uneven power delivery. Monitoring with a MB computer showed the Mass Airflow readings jumping from hi to lo and back....but should have shown it was somewhere in the middle. The MAS was fine, swapping it did no good.

I believe the root of the problem to be a crack in the circuit board or solder joint that causes erratic electrical connections. It was noticed when we had the covers off the LH module and plugged it in. My tech touched the board and it caused the TBA to react.

Anyway, I am back to the OEM chip in the new LH Module and life is good!

Thanks all of you for your comments, ideas and suggestions.

JimF · #14 02-10-2003, 11:25 AM

Bryan,

Since Scott (run.exe) needs a module to 'swap' in his 500E (stalling problem), would you be willing to send me your 'old' LH module so that I can look it over.

I'm pretty good at fixing this type of problem, pcb crack, bad solder, etc. If it is only that, then it possible that it can be repaired. If it is a bad 'chip (IC), then I probably will not be to repair it. But it's worth a try.

If you do this, please include a chip in the module that doesn't work. Also, will read and check the eprom to see if it's ok.

If I get it working (use my car as the test bed), maybe you can send this unit to Scott to test in his 500E.

Bryan Harter · #15 02-10-2003, 12:32 PM

Regarding SuperChips.....
I would not bother with them as a viable product in the states as the US group supports only US cars.

The reply I got from them this morning...

"Yes, the UK should be able to help you. We no longer support the European vehicles."