90 MTX cooling fan won't come on

[cfkull]

Originally posted in electronics, I think it really belongs here instead.


Have a BWD replacement IRCM so I don't know if it is equal to the M or not. Cooling fan was working, now it does not come on. Put power direct to the fan, nothing. Have a 3 wire single fan (from a 92 or 93 I think) that was in this car once before and worked. Power directly to it and it still works so I installed it with the connections from the IRCM going to the brown and high speed connections. Car still goes to the N in NORMAL and the fan doesn't come on. Replaced both the one wire and two wire sensors near the thermostat housing and no change, fan will still not come on. Any suggestions on how to check if the IRCM is sending the signal to the fan or not? No voltage at the fan connection when gauge is up to N. Ignition on, A/C on and cooling fan does not come on. Maybe when other fan died it zapped the relay in the IRCM, but KOEO test shows 11 which is supposed to be "no errors". Anyone know anything else I can check? This is my only transportation and I am sort of stuck until I solve the fan/overheating problem.

 

[PAracer]

This does sound like an IRCM issue. I have had problems with 'new' relay boxes. It seems that the same p/n is listed for all SHOs, which we know is incorrect. I have had good luck with used units from parts cars.

Aside from that, it could be a wiring issue. The early SHOs make use of fusible links.

Does the fan come on at all while running codes?

 

[92inPA]

The CCRM page on my web site gives all the details you need to trace out your circuit. As PAracer states, those "new" CCRMs seem to be rather generic, and don't necessarily work so well for certain model years.

Bob's CCRM page

.

 

[cfkull]

PAracer - no the fan does not come on while pulling codes, I thought it was supposed to.
92inPA - thanks, I had seen that before when I had a fuel pump problem, but couldn't remember where it was. Electrical stuff doesn't really bother me, but electronics do. When your write-up says something is on the "high" side, or "low" side, that goes right over my head.

On the M pinout diagram it says that pins 1&2 are the 12 volt power supply. I assume these are switched; hot with the ignition on? Is there 12 volt + on both or is one the - side? Same for 3&4 out to the fan, is one + and one - ? How do you check them physically? Probe the wire with a pin and check with a volt meter? Same thing when taking #14 to ground to force the fan to come on?

If I enter the Ford # E9DF-12B577-AB on Auto Zone or NAPA web sites I get BWD #
R4124. O'Reilly Auto Parts came up with BWD# R3174, but that also fits a 93-94 Probe, so I don't think it is the right one. On BWD web site if you do an application (1990 Ford Taurus is a precise as it gets) lookup you get a chart that shows a module for the 2.5 liter 4 cyl MTX (Taurus MT-5 1986, I had one) The R3174 that seems to fit all 3.0 & 3.8 cars EXCEPT E9DF--AA or AB which takes RCM21M which I suspect is the part that I want but no one seems to know how to order it. Does anyone have any information on these aftermarket replacements?

 

[92inPA]

I wish I could take credit for the CCRM writeup on my web page, but I can't. ProjectSHO89 wrote that up in a posting here on SHOforum. With his permission I have it posted on my web site intending to help folks better understand their CCRM.

On the M box: 1&2 are both hot (+12v) at all times. When the fan relay inside the CCRM is activated, 3&4 are both hot (+12v) to the fan. So, if you use a jumper wire to ground pin 14, the fan will come on. I believe (90% sure) this is the true, even with the ignition switch in the "off" position.

Allso note:
All years, all versions of CCRM:
Pin 15 is ground.
Pin 16 (A/C Coil low side) is connected to pin 15 internally.
Pin 8 is ALWAYS HOT.
Pin 13 is HOT in RUN/START.

 

[zerg1024]

i have the same problem as this except i changed out the relay for a ford factory one and it still doesnt come on. it comes on when i do the tests though so what could that be?

 

[zerg1024]

bump!!!!!!

 

[mfdspetz]

The SHO I just bought must have had the same type of problem as the previous owner wired a manual switch for the fan into the center console to turn the fan on when needed.

 

[zerg1024]

i mean my fan comes on but only when it gets up to the n and o

 

[SHOZ123]

high means open low means grounded.

 

[cfkull]

Thanks all. I found a good used "M" IRCM and now everything is working again. I think the BWD unit R4124 through O'Reilly Auto parts is not equal to the "M" even though their lookup (and Autozone cross reference ) both say it is the correct one. Any one else looking for this, the BWD RCM21M or Standard Motor Products / Blue Streak RCM21 appears to be the correct part, but they didn't have any stock available. SMP does have a repair service where you can send in your old one and they will return it within 48 hours.

 

[SHOZ123]

I have a good M CCRM if you need it.