new to the site so, I am bringing up a previously discussed thread. 2006 roadster - coolant light is on and fan checks good. Question is: where is the 50 amp fuse that other contributors have mentioned? Need to check it if, in fact, there is one. Can anyone help?

 

Does the fan spin when it's hot? If so forget the fuse.

 

The fuse is in the little box in front of the battery to answer your question, but what he ^^ said too.

 

Thanks for th replies. Fan spins only when jumped. There is no 50A fuse in relay box but,
have a 40. What do you think? Thanks in advance for the help.
frank

 

In the little box next to the battery are three fuses.

A 50 amp on one end for the Fan
A 50 amp in the middle that feeds the pulse module and the underhood fuse block on the driver's side.
A 200 amp that feeds most of the car on the other end.

I suppose it is possible that they changed the rating of the fan fuse during production, but the 05 manual says 50 amp and my 05 Limited has a 50 amp in that position.


Now, if the fan motor runs with power applied to it, and it won't run when the motor warms up OR when you turn the A/C on, then the Fan Module is bad.
The light indicates that the PTCM is not getting 'handshakes' back from the FCM OR that the FCM is reporting a problem.

Sounds to me like your FCM is bad. Make sure you have power to the FCM (you can measure it right at the FCM), if so, I'd say the FCM is bad.

 

In this box above the passenger front wheel.

large%20fuses%20box.jpg

50A (Radiator Fan & Traction Control)
Mopar: 05135816AA

05135816AA Mopar NONE FUSE $3.97
FUSE. 50 AMP. Relays, Fuses, Boxes and related items made by Mopar. #05135816AA

 

Needed the pic -looking in the busbox - fuse blown. Will change and see if it holds.
thanks for the help
frank

 

BTW folks, remember this is a HOT buss. Don't let anything (tools or anything metal) 'skitter' across these connections to GROUND. Besides almost making you change your pants, it could be extremely expensive to fix. When replacing any of these fuses, it is a safe practice to disconnect your negative battery cable (and remember you might have to reset a few things like the seatbelt chime software 'off'). Also, your 'emissions drive cycle' may have to run again so don't disconnect the negative cable if your going to have to run an emissions test soon. Safety FIRST!

 

Greetings XF guys! I'm new to the XF and this forum. My GF traded her son for a 2006 XF. He's off to coach a rural school and needed a bigger car. I've had some surprises reading about this 80% Mercedes vehicle. (Like why the need for two plugs per cylinder? I understand 2 valves...but not plugs! :-) )

Anyway, I've got the spoiler and the vert working for the 1st time in 4 years of ownership. Now, I'm looking at the cause of the coolant light. After reading on this forum, I looked for blown fuses and didn't find one. I turned on the A/C and the fan doesn't run. I unplugged the fan and jumped it directly. The fan works. The 50 amp fusible link for the fan appears in tact. So... It would seem the FCM must be bad -- though that's one of the few items already replaced by her son, the PO. So...I thought I'd break the ice and jump in to make sure I'm not skipping anything before looking for another FCM. (I guess I should verify there's a 12V feed into the connector for the FCM.

Oh yeah...What might cause multiple FCM failures -- if that's our problem?

I read the FCM is PW modulated to vary speeds. I see four heavy guage 12V (dual in/out) cables and two small voltage wires. I assume the later provides input for PW modulation of the output voltage. Since the car runs pretty well w/o the fan (except when calling for A/C operation), I wonder if that stupid thing couldn't be replaced with a simple 2-sp fan controller? Of course, IDK what type of signal is coming into the controller yet. I didn't measure it with my VO meter -- but maybe it's a digital feed?

Please let me know what to do next before looking online for ANOTHER FCM.

Thanks in advance for your help. Happy 4th and nice to chat with you guys! :-)

Gregg

(FWIW...My car is a fully customized 89 Vette with a 383 stroker pulling 440 ft/lbs of torque. Basically, I upgraded it to run like a Z. I've yet to delve into the luxury foreign car world being a Detroit fan. It will be interesting to see how this "Mercedes" thing pans out. I'm a bit concerned about cost of maintenance, but hey...the XF is a really nice looking sports car! )

Thumbs up!
:-)

 

Well, I realized the 50A fuse is really a fuse. To us "dumb guys" that have seen fusible links before, I guessed wrong. IMO, the engineer made a poor design because physical confirmation of failure requires the use of a continuity tester (which I have) or disassembly. (The window to the fuse is underneath and, therefore, not readily visible. That's about as dumb as shipping a b-load of cars with bad fans!) BTW... I used Chysler's website to confirm the supposedly replaced the fan within a year of sale -- per the TSB.

Yep, I'm a bit PO'd that it took too long to spot the "easy" problem. Of course, I had to have OReilly's send a replacement to the store nearby ($7). That's a bit high for a fuse too.

Next, I'll have to determine (or TRY to determine why the fuse blew). And, wonder if it will blow again. I'll Google the net and try to decide what target resistance is acceptable for a fan. (Yeah...it might be in the FSM which I spotted in this forum. Thanks for that whoever posted it!)

One thing I should clarify is there's NOT a fuse for the FCM in the DS fuse box. According to the FSM schematic, power to the FCM is supplied via that same 50A fuse used to power the fan. (I read some confusion on this.) Anyway, I guess the PTCM "sees" when the FCM isn't getting power and triggers theh low coolant warning light.

The fan will turn using short bursts of 12V via my battery charger. Then...after trying that, I saw the fan may actually have a 6V limit? At least the 5 stages of power peak under 6V. Hopefully, I didn't damage the fan coil (if not already failing). I only "tapped" the wires together to verify the fan would move. I didn't hold the wire together long enough to turn the fan more than a 1/4 turn with each tap. I only jarred movement. (That's because I didn't know what load my battery charger could handle! LOL At least I know my charger has an internal resetable circuit breaker.)

Tomorrow, I will measure fan coil resistance and, likely, install the replacement 50A terminal fuse....unless I determine can coil resistance is too low.

 

89Vette, I measured the resistance on the spare fan motor I have and it measures .0001 ohms, same as when I hold the meter leads together.
So if you measure any ohms at all, there might be a problem with the motor.

 

The fan runs on 12 volts from the FCM. There is an ignition sense lead that turns the FCM on, and a "PWM" lead that comes from the PTCM.

The PTCM sends a tickle pulse to the FCM every few milliseconds. The FCM responds with a pulse. As long as that happens, the light stays out. If the PTCM does not get a pulse from the FCM, it lights the light to tell you that you have a cooling system problem.

The width of the pulses from the PTCM tell the FCM how fast to run the fan. The FCM sends pulses of 12 volts to the fan motor (your meter will average these pulses and imply to you the fan is getting 4 or 5 6 volts, but that is not the case). DC motors do not do well on low voltage, they do better on pulses of full, normal voltage to control speed. I have a switch in my car that breaks the PWM wire connection - this makes the light come on, and it ALSO means that the FCM does not see the pulses from the PTCM - this makes the FCM go into emergency mode (because it no longer is being told what to do) - and the FCM puts full voltage on the fan motor and it runs like a turbine!

Oh, most likely reason the fuse blew was that the motor is going bad and drew too much current. It COULD be an issue with the FCM, but I really think it's the FCM- but it's hard to say from here.

Hope all of this helps.

Oh, and Bacon. Always eat bacon.

 

How did you determine the PTCM sends a digital signal to the FCM? Since the FCM looks to contain the parts necessary for PW modulation, I am thinking a variable input (or ground) voltage could signal the FCM what to output. (I suggested ground voltage since that grey wire is the ONLY connection to pin 39 of the PTCM.) I suppose that FCM could be "smart" enough to decode/deliver bi-directional information from the PTCM but it SEEMS that one-directional variable DC voltage would do the trick.

I couldn't find a DETAILED description of the actual FCM function. I'm just an ex EE major that jumped over the CS in the 80's. You know...the kind that makes wild guesses out the wazoo! :-)

FWIW, I replaced the 50 amp control block fuse today and it's working property for now.



(In my 89 Corvette, the ECM triggers a simple relay for the 1-spd main fan. The aux fan is triggered via engine block sensor. Ahh....for simplicity! LOL Now that I know about these 50 amp "MIDI" fuses, maybe I'll use a couple of them to redo my Corvette's fan circuit. I want to convert to a more powerful 2-spd puller fan after building the stroker motor. The pusher non-shrouded aux fan seems fairly worthless.)

Thanks for the help guys!

 

With an O'scope and 31 years experience in these matters. And one direction does not do the trick because the PTCM has to know if the FCM is working, otherwise it would not know the FCM is "gone" and would not know enough to light the light.

The "PWM" line from the PTCM to the FCM is a digital bidirectional bus. The "tickle" pulses from the PTCM get "fatter" as it wants the fan to turn faster. Very short pulses (I cant remember, I think something like 5 ms) are the baseline. These are "I'm here watching you" pulses only. Once you turn the A/C on, the pulses get a lot wider, indicating that the fan should turn at "minimal" speed to assure the condenser can dissipate heat. Let the engine warm up good and you will see the pulses get even wider.

The return pulses from the FCM did not appear to get wider, no matter what, it would appear the PTCM is happy just knowing the FCM is still 'talking' and assumes in such cases that the FCM is operating the fan as it is being told to.


I've lost my notes, I did the homework two residences ago on my first Crossfire (the original red roadster, the one missing one pedal).

 

Thanks for the feedback/info....and glad you bought another XF with that extra pedal! :-) Maybe you need one with an extra fan too! (on the intake)

:-)

Thanks again!

 

The Ford Ranger I just bought could use one, it has the mechanical fan and at idle in the Georgia heat the A/C does'nt cool like I'd like it to.

Been thinking about this...

 

The "extra fan" I was talking about was a sneaky reference to the superchargered models! LOL

 

First post, just bought my 2006 Coupe Crossfire. I had to fit a new battery and in doing so I dropped in in backward and the earth toughed the positive terminal and sparked.

I fitted it the right way round and the add coolant light came on and I noticed that the fan isn't coming on. On reading through here I think I have blown the fan control module. I couldn't find in this thread where the fan control module is located. Could some one help please?

 

It is on the driver side fenderwell ( follow the wire back from the fan )

 

Thanks. The reason I couldn't find it is because the previous owner had fitted HID lights and the box for them was placed on top of the FCM so camouflaged it