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2015 Jeep Patriot - How are the radiator fans activated?

12K views 9 replies 6 participants last post by  Irontooth  
#1 ·
There are 2 radiator fans. There is a high speed and low speed relay in addition to temp sensors. Does activation of the radiator fans depend on temp, speed, or both?
 
#4 ·
Welcome MrBob,

Welcome MrBob,

According to the manual, it's both

View attachment 92616
Welcome MrBob,

According to the manual, it's both

View attachment 92616
Thanks alot RonD !!
Per schematics I saw... C1 is the fan on the 'driver' side of the radiator and is the Low Speed fan. C2 is on the Passenger side of the radiator and along with the C1 make up the 'High" speed eg 2 fans running instead of one. With A/C on both C1 and C2 run. Warming up the car and then turning on A/C with the car stopped allows you confirm that both fans are running. The Power Relay Module has a serial / parallel relay that is activated when 'High Speed' criteria is determined... I believe that this relay puts 12 volt power to C1 using the same power ckt that is used by C2. If any of the relays fails then the 2 fans will not work properly or at all leading to overheating probably. In my case Low Speed Relay had a corroded power terminal and I cleaned and replaced the terminal and the Relay... All 4 relays receive 12v power thru Fuse 33 in the fuse module; power to 3 of the relays are tied directly together, this voltage is there always when ignition key is on. Each Relay activation signal (the other side of the relay coil) the computer goes to a logic low (ground) for each of the relay activation signals to complete a circuit. Power for fans C1 and C2 is via Fuse 15, then to the relay; when relay is activated this power is sent to the appropriate fan and the other side of the fans goes to ground completing the circuit.
MrBob
 
#8 ·
My first suggestion would be to test the fans with a bidirectional OBD scanner or an OBD app such as JScan. If you can switch the fans on this way, it indicates that the relays and related circuitry are working properly.

Next, check the grounds that are on a stud just below the driver side hood stop, in front of the battery. The one with fewer wires grounds the fan Series/Parallel relay. The grounds tend to get corroded within the wire crimp for the ring terminals. It’s not necessarily visible to the naked eye, but if you have green corrosion products showing between that crimp and the one for the insulation, there is a good bet that you have a problem. The fix is to cut off the ring terminal and attach new terminals.

Also, check the relay box behind the driver side headlight. It’s an oblong black box. The top pops off when you pull one of the tabs away from the box and pull up. Pull each relay and look for corrosion products. If found, you’ll have to replace the affected relay and clean the socket as best you can. The corrosion can also affect the socket terminals and wires that the relay plugs into.

Resources:

JScan - http://jscan.net/

Grounds - I see that Sandstone already linked to one reference; Here’s how I handled the repair:

Relays - https://www.jeeppatriot.com/posts/1909682/
 
#10 ·
This is maybe too much information, and it requires a bi-directional scanner (or OBD adapter and app such as mentioned above), and a circuit tester (or multimeter equipped for circuit testing) but…

Note: The different resources reference different years from the 2015, but they should be pretty much the same.

This post contains a drawing of the relay box identifying the relays:


Here’s a link to the Radiator Cooling Fan Testing and Inspection procedure from the online Operation Charm service manual for the 2010 Patriot:


Here’s a post from a thread on wiring harness, connector and component locations showing the radiator fans:


In the wiring diagrams, each wire trace shows three bits of data. Top to bottom they are: Reference Code (e.g. from service manual), Wire Gauge, Wire Color(s). Also, different modules are usually outlined with dashes, and the connector ID and pin number are shown where the trace exits the module.