Jkw

On my 2004.5 c230 the rear defrost stopped working.
My mechanic doesn't believe the problem is the panel control unit, as every thing else works.

Suggested it might be the Rear Sam.

I've done a search and was unable to find the part on any MB part site.

What can anyone tell me about the Rear Sam??
Does anyone have the part #?
Thanks Jkw

Glyn M Ruck

Have you had a tint done recently? Sometimes they cut the element traces in the rear screen when trimming the tint (& antenna wires)

acr2001

Like Glyn said, a broken element is most likely. However, you can have someone stick their head in the trunk and listen as you turn the defroster on and off. There should be an audible click from the relay which is located on the rear SAM unit with the fuses.

Do you have a voltmeter? That would be the fastest way to track down the problem.

Jkw

No Tint,

Thanks for the tip about the audible click from the relay,
I'll try that today.

voltmeter, I'll have to get one.
Thanks

Glyn M Ruck

OK - no tint - good news - If the solenoid clicks - Check connections on screen.

Jkw

Yes. I did hear the clicking.
I assume that means the solenoid is working??

If so, than the problem is in the wires after that point,
and not with the Rear Sam, Correct?

Off to get a voltmeter.

Thanks Jkw

Jkw

I found the Rear Sam
Where would the Rear Defrost Solenoid be located?
As you can tell, I've never done this before, and don't want to just start pulling on the wires.

What's the best way to remove it?
Thanks

acr2001

Honestly I'm not sure which one it is. If you search the forums for a fuse diagram I believe it includes labels for all the relays. You should be checking the connections at the glass as Glyn said. I think those connections are at the top of the rear window behind the headliner. You might be able to stick your head back there and see inside with a flashlight and then get the voltmeter leads in there. I'm not so sure though as I haven't tried getting behind the headliner back there.

Jkw

I found this

For the rear SAM:

Relay Cavity

A Fuel Pump Relay
B Relay 2 Terminal 15R
C Reserve Relay 2
D Reserve Relay 1
E Rear Window Defroster (STD on BMW's, keeps hands warm while pushing)
F Relay 1 Terminal 15R
G Filler Cap Relay Polarity Reverser 1
H Filler Cap Relay Polarity Reverser 2

Thanks for the suggestion, I'll have to check the headliner.

MBtech1098

Just replaced a Rear SAM for this exact concern last week. The relay is in cavity E, and the fuse is #10 40 amp.

acr2001

I don't want to hijack this thread, so I hope you don't mind Jkw.

With this snowstorm, I noticed that if my rear defroster is on along with the front defroster and heated seats, my battery voltage drops down as low as 12 volts (WITH THE ENGINE ON!). As soon as I rev the engine even a few hundred RPM above idle, the voltage kicks right back to 14 -14.5 as it should be. Without the rear defroster on I do not have this problem.

Is this a normal thing because the alternator is a little undersized, or should I be checking my alt / voltage regulator / battery?
The battery is 5 years old, original -- maybe it's adding resistance to the circuit due to its age? Thanks.

MBtech1098

The rear defroster on the car puts a tremendous load on the electrical system...it's protected by a 40 amp fuse! So if you have a lot of electrical loads on at idle the voltage will drop. Max alternator output is usually around 2000 rpm's +/-. BTW-the front defroster does not carry much electrical load, besides the blower motor itself...that heat comes via the heater core.

Jkw

No Worries

Again thanks for the information

Jkw

Do you have a part # for the REAR SAM?
& where I can get one besides the dealer,
Thanks

acr2001

Yes, this I know. I'm just wondering if anyone else has a similar outcome at idle with the heated seats, rear defroster, and fan on full. Thinking about just getting a new battery since it's pretty old, but I don't want to waste my money if I could get a few years out of it.

MBtech1098

There are too many variants to give you a part number without the VIN. If you shoot me a PM with the VIN, I can get you a part number. As far as where else to get it, I would have no clue, it is a pretty manufacturer specific part. There is also some codings that need to be set via SDS.

If you have a factory battery, they say they last about 4 years on average.

Jkw

Thanks, I pm you the VIN.

Does that mean it's not a DIY job?
Could a competent shop handle the job?
Or do you have to go to the dealer?

Thanks
Jkw

Mario Gamer

Black wire on sam is problem

Preet

Which black wire the ground wire?