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  #1  
Old 09-22-2003, 05:04 PM
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'97 E420 - Auxiliary Cooling Fan Activation

What controls auxlilary cooling fan activation on a '97 E 420 (210.072)... relay? cycle module? control unit?

The control module found behind the headlights (027 545 80 32) on other models is not present on this vehicle.

Is there a cycle module (perhaps N65) that is responsible for activating the fans? If so, is this module located in the electronics bay near the front windshield?

Or is fan activation integral with the MSG (ME 1) control unit?

The fans are functional when provided external power but fail to run when the A/C compressor is activated or engine coolant temperature is elevated.

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  #2  
Old 09-22-2003, 06:21 PM
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Should have 210-545-03-32 fan module in the fuse box.
That module gets its commands from the ME-SFI(fuel system) control unit.
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  #3  
Old 09-23-2003, 11:41 AM
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The 96-97 210's can be a bit tricky when it comes to the fan operation. A quick way to identify which system your vehicle is fitted with is to look at the left front frame rail just behind the bumper. A large aluminun looking control module may indicate that you do not have the "Cycle Module" if memory serves me correctly.

The other, most always absolute way is to go by the VIN and the production date.
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Old 09-23-2003, 02:35 PM
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M.B.Doc is correct - the vehicle is equipped with the 210 545 03 32 module.

But... is there any way to check the functional status of this module, short of installing a unit of known quality? A new module lists for over $220.


The cycle module's function is not monitored by M-B's HHT but one can easily check for aux. fan activation points:

1) Minimal aux. fan - control current of 2 mA
- engine coolant temp > 95 deg C or
- refrigerant press > 14 bar

2) Maximum aux. fan - control current of 10 mA
- engine coolant temp > 115 deg C or
- refrigerant press > 20 bar

Fan energization voltage can be checked at the module's D1 & D2 pins. And, of course, fan power harness continuity can be easily checked at that point - the harness that plugs into D1/D2 runs straight to the fan motor.

But, if there is no power at D1/D2 and fan activation criteria is met, do the pros do any additional testing? Or do they drop in a new cycle module at that point?
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Old 09-23-2003, 06:17 PM
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If you put power & ground directly to the fan assembly will it come on?? IS there power & ground at the fan control module??
If so then the fan control module is the next step.
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  #6  
Old 09-24-2003, 04:32 PM
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Installed new fan control module from M-B... with A/C engaged and coolant temp > 95 deg C, aux fans ran for about 1 sec and then stopped.


Vehicle is a '97 E420, with a production date of 11.97 (production ran late due to late EPA approval of E430).

Fan control module has six groups of pins (A-F); each group contains one or more pins. All groups are used except for group C.

With key on, module is receiving constant 12V at pins A1 & A3; pin A5 is a dedicated ground. Group D (two pins) is the dedicated power supply to aux fan.

Group E consists of 7 pins, all of which are used; function is unknown. Group B has 2 pins; group F, one pin.


Aux fan runs when module is bypassed and power/ground are supplied directly.

With engine on and aux fan activation criteria met (confirmed using HHT), voltage at group D is 0. However, module can be heard and felt to click on a regular basis; approx 1 sec after the click, the voltage at group D momentarily jumps to approx. 8.6 volts and then quickly returns to 0.

Internal inspection of the old module revealed no gross defects.


Any idea as to whats happening here? What should be checked next? Is a signal feed to the module causing the fault or is the new module defective (although wrapped in padded paper and received in a sealed box, the upper plastic lip of the module was cracked; a corresponding gouge was noted on the interior of the box)? TIA.
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Old 09-24-2003, 05:54 PM
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Try peeking behind the bumper and see if the left side frame rail has an alimunum box anchored to it. If so that could be the culprit, if not than it may be attached to the fan assembly with the fan.

Would you happen to have accesory number (A/C 580 or 581a) to identify the system fitted to your car? Is your fan mounted in the front of the condensor or is it mounted on the engine side of radiator?

My information shows a couple of different systems can be fitted to that production range of vehicles. Production date and A/C code number easily identify the system on your car.

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  #8  
Old 09-24-2003, 08:13 PM
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The easiest way to test it in an MB shop is to go into aux fan activations screen in climate control, You can activate the fan in that screen as a test of the whole system.

Gilly
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  #9  
Old 09-24-2003, 08:51 PM
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MrCjames - no mention of 580 or 581a is in the data card; in fact, no codes at all specific to climate control option. EPC does show the vehicle to be equipped with the "Elegance" package, which did include automatic climate control as standard (vehicle is a U.S. model). Production date is 11/97, per the door jam sticker. No aluminum box is present on the left frame rail or adjacent to the fan motor. Aux fan is mounted in front of the A/C condensor.

Gilly - used an HHT yesterday on this vehicle and don't recall seeing a test for aux fan activation. Only found a data page detailing the fan activation points. Was that test feature available on the '97s? Will recheck tomorrow.


Thanks for the help.
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  #10  
Old 09-24-2003, 09:30 PM
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Yes, you should see it in the climate control face screen, go into climate control (ACC I believe it's called on a 97, it's always the "last" choice), and click on actuations.

Gilly
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  #11  
Old 09-25-2003, 11:23 AM
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Follow Gilly's advise on the HHT operation, it is in AAC-Actuations.

Reviewing my info, and your fan being mounted in front, you should have a controller mounted directly behind the left headlamp (N65/1) 6 connections. To the right and forward of the ABS hydraulic pump assembly. If the unit is there than I believe that it may be the culprit to your fan operation issue.

From this point forward Gilly will be able to provide you with more assistance because some of my info may be outdated.

Good Luck

Last edited by MrCjames; 09-25-2003 at 11:43 AM.
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  #12  
Old 09-25-2003, 07:20 PM
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Gilly - used the HHT to attempt activation of control module N65, which controls the aux fan. The HHT activation offers 4 stages (stage 1, 2 mA; 2, 5 mA; 3, 7 mA; and 4, 10 mA).

The aux fan failed to operate with either the old module or the new one when commanded to activate by the HHT. No current was detected at the 2 pin D group on the module, which supplies power to the aux. fan.

However, a relay click, within the module and cycling every 6 seconds, was noted. Removing the cover of the module reveals 3 separate relays. The middle relay was the unit cycling... the relay would close for 6 seconds, briefly open and then close again.

But still no fan activation... unless the fan is supplied 12v directly.

So, since the activation failed, is it safe to assume the new module is bad? Or could have something possibly have fried it, since the fans worked for about 1 second when the new relay was originally installed?

WIS shows that the aux fan cycle module on this particular model receives elevated refrigerant pressure and engine coolant temperature info via the climate control pushbutton control unit. Does the HHT bypass this and directly command the aux fan cycle module to activate?

Given the results so far, what should be the next diagnostic step? According to WIS, all data the pulse module receives comes from the AAC pushbutton control unit... should that unit be swapped out?


MrCjames - this vehicle was produced in 11/97 and I can find no reference to it in any M-B service literature. I suspect that since this was an extended run of an existing product at the end of its production cycle, no changes were made and the vehicle can be treated as though it were a 210.072, with 119 engine up to 9/97.

If so, then according to the "Electric Test Program - Connection of Components" found in WIS...

Connection of Components for Aux Fan (M4) Regulation
Model 210
Engine 119 up to 9/97

A1 - Instrument cluster
B11/4 - CT sensor
B12 - Refrigerant pressure sensor
M4 - Aux fan
N3 - CFI control module
N22 - ACC pushbutton control module
N47 - Traction systems control module
N65 - Pulse modulation (traction systems, HCS, ATA, AAC)


Instrument cluster & refrig pressure sensor report to climate control pushbutton module; the pushbutton control module communicates with the pulse module, which in turn powers the aux fan.

The engine coolant temp sensor reports to the CFI control module, which, via CAN, communicates with the instrument cluster and the traction systems control module. Elevated engine coolant temp is subsequently passed from the instrument cluster to the climate control pushbutton control module to the pulse module, which then commands aux fan operation.

No reference is made to a frame rail-mounted engine/climate control electric cooling fan control module on this particular vehicle. It is shown, however, on 210s with M112 up to 5/98 and M113 and OM606 up to 3/97.

Thanks to both for your continued assistance.
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  #13  
Old 09-25-2003, 10:14 PM
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The first thing I think of, and sorry if this seems too basic, is the big 40 amp fuse for the aux fan in the main fusebox. Another thought is that if the fuse checks out fine, is I believe that relay in the rear of the fusebox plugs into the botton of either the LF SAM or maybe it's just considered a fuse and relay panel. If the relay doesn't plug into the fuse and relay panel, then the 40 amp fuse does. The problem I've seen is water getting into the fuse and relay panel and causing various electrical problems.

Sorry I'm not all that well versed or at least had alot of experience with this exact setup, I'm more familiar with the 210's with the fan control module in behind the left side of the front bumper, I've tested and replaced lots of those modules.

Gilly

The fuse I'm talking about is called a "Maxi-Fuse", looks like the rest of the fuses in the box but much larger.
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  #14  
Old 09-26-2003, 12:42 PM
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Aux Fan

I am going to follow Gilly, explore the basics one more time.

Your fan is mounted in the front therefore it is classified as an Auxiliary Fan.

Re-examine fuse number(s) F1#20[30A],#7[15A]#4[10A] all in the front fuse panel.

I take it you do not have an electronic module mounted near the ABS hydraulic unit?

Also did you jump the fans at the radiator connection or did you jump them at the electrical connector of the control unit that you replaced?
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  #15  
Old 09-26-2003, 01:16 PM
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That's my confusion with this whole thread. if Donnie says the fan control module is in the fusebox I'm not going to argue, but I don't recall seeing one there, but for some reason it does sort of ring a bell with something I read somewhere.
Maybe the fusebox was actually a better location for it and never caused any problems when it was mounted there?
What I'm familiar with replacing is the one right behind the bumper bar itself on the left, you need to remove the left front wheel and remove what I call the front bumper apron, the black plastic panel under the front bumper, and also usually remove a few of the nuts/screws that hold the front splash pan to the inner fender structure. It's a finned aluminum box held down by 2 10mm nuts, one big "racetrack" shaped electrical connector. 2 large wires leading to the fan motor are the output wires, also has at least 1 large dia. wire which is coming from the 40 amp maxifuse to power up the fan, and the module I agree is controlled from the engine control unit, sends either a voltage coded signal or a cycle signal. If the fan runs with battery power jumped to it, fine, at least it does something, although I have seen them run with power jumped to it, but they wouldn't run "100%", which I guess you learn by experience if they are running full speed or not (sight and sound), and on this one case, the fan motor assembly fixed it. On that one, if I used activations to run the fan 100% it would run, but not anything lower than 100%. You gave it 100% and it would "sorta" run, there is nothing in WIS to tell you any of this. By "sorta" run, I mean I wouldn't want to stick my finger in there or anything, but it wasn't "howling fast" like a good running motor would give you.
Hope this helps. Hopefully the only real difference between what Donnie is saying and what I'm familiar with is the component location, maybe they though it would stay cooler outside the box or something, or wanted short output wires. Maybe they were just thinking "outside the box" .

Gilly

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