M104 updated lower wire haness. - PeachParts Mercedes-Benz Forum

244brick · #1 05-18-2015, 05:57 AM

I need the one that plugs into the ETA and etc.
Also need an e-gas computer.

For a 94 E320 estate.

David Hendy · #2 05-18-2015, 07:58 AM

For a definition, the "lower harness" is as far as I know the one that connects to the starter, the oil pressure sender and the oil level sender.

The ETA harness, or "body harness" is a whole different barrel of bees wax, it connects the ETA, runs up to the fuse box, then under the dash, up over the heater box and down into the passenger foot well to the ETA computer or "e-gas" unit. Only way its being replaced is with the dash out of the car.

Unless you have completely stripped one of these cars apart, it is very difficult to retrieve the body harness.

It is also, ASR or NON ASR specific, as well as 48 state or 50 state specific (the 50 State cars have the carb relay under the dash).
so you should really access the EPC with your vin and get an accurate part number.

97 SL320 · #3 05-18-2015, 06:51 PM

While we are on the subject, does a non ASR car have an e gas computer? If so, does that just run the cruise control?

David Hendy · #4 05-19-2015, 07:25 AM

Yes non asr cars have an egas. But its smaller than the asr one (about half the thickness), and yes it pretty much just runs the cruise control.

The ASR car has a 2nd harness that connects to the egas unit, so the wiring is twice as complicated.

On the C36 M104 engine swap kits I have put together, using the 1993 or 48 state non asr M104 harness to run the 3.6 engine is much much simpler than the later or asr equipped cars.

Not sold in the US was an M104 without cruise, which had no egas.

244brick · #5 05-19-2015, 09:19 AM

Sorry it is non-ASR. I did not realize thats how it was set up. Also did not realize the e-gas computer was only for cruise control. I am trying source the mechanical failure that is limiting my rpm from passing 2500. I have just put a 96 eta on it. Replaced the upper main harness.... but the problem persists.

David Hendy · #6 05-19-2015, 11:52 AM

The '96 eta, is it tested known good?

I would get your hands on a known good main ECU (behind the battery) and a non asr egas (under the front passenger carpet).

Plus while your at it, if you don't know the history on the alternator, change that as well. I have cured several strange eta issues by changing the alternator.

97 SL320 · #7 05-19-2015, 09:25 PM

I've fixed several cars over the years where a bad diode introduced AC into the electrical system with all sorts of strange results. This has even occurred on simple cars that just had electronic ignition.

badgator · #8 05-23-2015, 09:54 PM

Every e320 ETA I have found with a date on March 1996 and older (96M03) have had defective wiring.
I am not certain of the cutoff date may be a couple months newer.
Either pull off the side of the ETA and check wiring or very carefully make a small slit in the outer insulation to check the wiring insulation and use self fusing silicone tape to repair if good.

David Hendy · #9 05-28-2015, 11:29 AM

I thought this might help.

Its a picture of the eta "body" harness for an M104

In the foreground of the picture is the eta, the cruise control switch and the brake pedal switch.

To the rear is the eta ecu or "egas". The harness between the two runs up and over the blower box under the dash.

As you can see the wires are good. This is from a '94 without ASR, a 48 state car without the CEL.

244brick · #10 05-28-2015, 04:20 PM

I need to over look everything more thoroughly when I have the time. Im going to make a junkyard run and see if I can score an egas comp and maybe an alternator if i can find one the looks newer then mine. Is there any higher output alternators the are install compatable off possible a different model?

244brick · #11 05-30-2015, 06:35 PM

Eta wire on the body side actually looks ok externally... i have cut the sheeth open though. Theres wires that run along the firewall right behind the cylinder head that are in bad shape... ive just been so busy i only got to glance at it to check the ETA wire.

Stevester 500E · #12 10-02-2015, 12:46 AM

David,
What if one was swapping a c36 motor to a m104 asr car, why does it become more difficult? Or does it?

Quote:

Originally Posted by David Hendy

Yes non asr cars have an egas. But its smaller than the asr one (about half the thickness), and yes it pretty much just runs the cruise control.

The ASR car has a 2nd harness that connects to the egas unit, so the wiring is twice as complicated.

On the C36 M104 engine swap kits I have put together, using the 1993 or 48 state non asr M104 harness to run the 3.6 engine is much much simpler than the later or asr equipped cars.

Not sold in the US was an M104 without cruise, which had no egas.

David Hendy · #13 10-02-2015, 08:24 AM

Its no harder its the same. Only difference (as far as the engine is concerned) is the ASR throttle body. So on your install, as long as you use an ASR throttle body its exactly the same.