Today I was checking the operation of the electric cooling fan on my 2005 KJ CRD

By using a handheld tachometer and jumping terminals 87 and 30 on each of the High speed and Low speed fan relays, I was able to ascertain that for some reason there is NO fan speed difference when jumping the relays.

On other words, when jumping EITHER relay, the fan turned on and ran at 2000 RPM.

Of course, I was expecting the fan to run at different speeds depending on which relay I jumped, but that was NOT the case. Pics below.

The question is WHY??

Is 2000 RPM the normal HIGH speed or is it the normal Low speed?

Anybody have an idea??

_________________
Horses in the stable:

"Giddyup" is my 2005 Liberty CRD
"Maya" is my 2005 Dodge Ram 2500 CTD powered by the mighty Cummins ISB 5.9 with 6spd G56 manual trans
"Mr Ed" is my 1980 Toyota Pickup Flatbed, 20R engine, 4 speed manual, NO power steering, NO A/C

Check the voltages going to the fan at the different settings.

_________________
GDE FT Ecotune, EHM, Weeks kit stage 1 & 2, Carter 4600 lift pump, Upgraded tranny, Fishing boat hauler!
New at 164K: head gasket, rockers, exhaust valves, ARP head studs, Injectors, 5v Bosch glow plugs, water pump, timing everything, serpentine everything,
New at 225k: new head, timing belt

This system has never made a lot of sense to me. If you pull either one of the relays, high or low speed, the ECM will energize the single relay still in place and the fan will run. Not sure why this is as the wiring diagrams does not provide any answers.

Just a wild guess!
Without testing on my own, it may require both relays energized at the same time to get high speed and either one of the relays singularity to get low speed?

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

Will do that today and post back.

_________________
Horses in the stable:

"Giddyup" is my 2005 Liberty CRD
"Maya" is my 2005 Dodge Ram 2500 CTD powered by the mighty Cummins ISB 5.9 with 6spd G56 manual trans
"Mr Ed" is my 1980 Toyota Pickup Flatbed, 20R engine, 4 speed manual, NO power steering, NO A/C

Interesting...if the fan is rated for 24v and if the relays to the fan are wired in SERIES, but then again how would that make sense since the Jeep has only ONE 12v battery powering BOTH relays.

Or perhaps the fan motor has TWO windings and each relay energizes one of them. I think that this is more likely!

I will disconnect the fan and try energizing the relays individually and combined while checking the voltage at the fan connector...

Still, this is a little hard for me to wrap my brain around,,,MAYBE that is why there is a 3 pin connector for this fan?

I know you said that the fan wiring diagram doesn't show anything decisively, but do you have a link to the wiring diagram??

TIA

_________________
Horses in the stable:

"Giddyup" is my 2005 Liberty CRD
"Maya" is my 2005 Dodge Ram 2500 CTD powered by the mighty Cummins ISB 5.9 with 6spd G56 manual trans
"Mr Ed" is my 1980 Toyota Pickup Flatbed, 20R engine, 4 speed manual, NO power steering, NO A/C

Jeep online manuals:> https://www.colorado4wheel.com/manuals/Jeep/KJ/

See 2005JeepKJServiceManual.pdf, section 8W for wiring diagrams.

This is my custom drawn cooling fan wiring diagram showing all components.

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

EXCELLENT, thank you !!!

I will print a copy bring it with me when I check the relay voltages again today

_________________
Horses in the stable:

"Giddyup" is my 2005 Liberty CRD
"Maya" is my 2005 Dodge Ram 2500 CTD powered by the mighty Cummins ISB 5.9 with 6spd G56 manual trans
"Mr Ed" is my 1980 Toyota Pickup Flatbed, 20R engine, 4 speed manual, NO power steering, NO A/C

Winner, winner, chicken dinner !!!

After staring at your excellent fan wiring diagram, I decided that eihter the relays are wired in series OR that the fan motor has TWO sets of windings , one relay powering each winding.

NOT sure which it is yet, and leaning towards the latter, but by energizing BOTH relays at the same time, (NOTHING blew up ...another WIN!!!) the fan started spinning at 2400 RPM instead of just 2000.

Pics or it didnt happen --

_________________
Horses in the stable:

"Giddyup" is my 2005 Liberty CRD
"Maya" is my 2005 Dodge Ram 2500 CTD powered by the mighty Cummins ISB 5.9 with 6spd G56 manual trans
"Mr Ed" is my 1980 Toyota Pickup Flatbed, 20R engine, 4 speed manual, NO power steering, NO A/C

Good find. The problem with these Jeeps is that there are so "black-box" modules with very little indication of what they're doing, so looking at the wiring diagrams almost always inadequate, and in many cases the descriptive text is also insufficient.

_________________
2005 Liberty Limited CRD; Air Filter Monitor; Samco Hoses; GDE HOT Tune; RL037142AA TC; KJ Interior Rack from All J Products; JBA Adjust-a-strut lift and A-Arms; 245/75R16 Firestone Destination ATs on Moabs; ARB Bumper; ASFIR Skids; FS-2500 Bypass Filter; ARP studs.
2016 Grand Cherokee Overland CRD.