texass600

I have an 03 s600 and am considering buying another and was wondering if I can swithch out the Renntech modded CPU with the CPU from the unmodded extra 03 s600 I will buy and the unmodded back into the previously modded one . Essentially, can I swap computers with 03 s600's?

Thanks in advance for any help.

c131frdave

Are both cars the same year?

My bad. I reread the post.

I'm a noob, but I would say yes. I've been playing with ECUs on other cars for 20 years, and have done this many times- but never on a Merc. The Germans might have some fancy something something to screw up your plans, but it shouldn't hurt to try.

Oxygen

Okay, and I would say no you can't.

The ECU is VIN coded to the vehicle and is tied into the car in many other ways. You will need to have a tuner re-code it for you. They usually do that for about $100 or for free.

Oxygen

Call RENNtech at 561-845-7888 and they will tell you the price for a re-code.

c131frdave

Not sure why you would say that. A vin code is nothing more than a set of alphanumeric numbers that track your vehicle. A computer certainly cannot read your VIN code if you put it into a new car. Perhaps if you have your programming saved by your tuner in their computer under your old VIN code, that could be a problem finding the software during a re-tune. The only other problem I could see is if the ECU is directly in control of some optional device on the old car that is not on the new one, or the new one has an optional device that is controlled by the ecu that is not on the old one. But that is simply a matter of enabling the device.

Before I managed power plants, I was an Instrument and Controls technician for GE Energy and Cummins. While you may not have expertise on how exactly to do it, I assure you a simple automotive ECU can be customized to do whatever you want. And I'll bet five bucks it'll just plug and play.

whoover

You really need to watch your money. The ECU and EIS are both coded with the VIN. The start protocol includes the EIS confirming that its VIN matches the ECU's. If either EIS or ECU is ever replaced, it must be coded with the proper VIN.

There are all sorts of other reasons that an ECU might not work having to do with production changes mid-year. When you order a replacement from the dealer, they need your VIN to make sure you get one that works, above and beyond the VIN-coding.

whoover

BTW, just to be clear: only a new ECU can have a VIN programmed. The VIN is burned into WORM memory (write once read many) so it cannot be recoded to work in another car. All of this is part of the theft security system that MB uses.

A used ECU is useless. Same with a used EIS.

Carzy

Hi! I have a 2003 S600, 34000 miles. It sits on a battery tender when not used. Recently, after sitting about a month, I kept getting a warning about the suspension and to take it to my dealer. I took it to the dealer, he reset the computer and the warning's gone....but he said it may come back and I'll need a new computer ($5000. ?) or I may never see the problem again. Qustions: (1) might the battery tender contribute to this problem and (2) if it does, could I install a battery cut-out (the type that fits on the neg. terminal with a green knob), with a low amp fused by-pass wire to keep the computer "alive"? thanks.

whoover

How long do you leave the car sitting? A good battery should be able to sit for months and still start the car.

Did the dealer say what "computer" might be the problem? It doesn't sound like an ECU problem. Front SAM? ABC control module? Or is the dealer just guessing?

I can't imagine a battery tender causing any problem if it's decent quality. As long as the voltage is ok and it's clean DC, the electronics won't care. Most of them are not on when the car is sleeping anyway.