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A while back there was a good write up for installing a switch to turn on the aux fan manually, that included a diode. On the 96 and newer it is ground activated, so I was a little confused on what I found when I searched. Can someone please clarify the wiring and parts needed.
By "ground activated," I assume you mean that the fan RELAY is always hot, and the relay is turned on and off by the PCM opening or closing the ground side of the control coil? The fan itself is still controlled by a relay in the 12v positive side, and grounds directly from the fan to the chassis.
If that's correct, you don't need a diode. The flow is positive to negative. You can wire a switch in parallel with the wire from the ground terminal of the relay to the PCN, then from the switch to ground. It can't backfeed the PCM because electricity doesn't flow in that direction.
If you're ultra conservative, use a SPDT switch that will disconnect the PCM wire when you throw the switch. One way will be manual override, the other will be normal operation. No interconnection.
Eagle, thank you for the reply.
I am going from memory on the specifics. How do I determine what it actually is?
The SPDT switch is a good idea, I had not thought of that route.
In your senario;
Relay to battery(12V power)
Relay to chasis(ground)
Relay to switch
Relay to fan
Do you know the correct numbers to connect to for the above?
i just spent a half hour reading and i cant find a straight answer here i have a 1994 cherokee and can't figure out how to wire in the relay and switch so it will work on one setting when i turn on the switch and it will work on another setting it will work as in stock form.
I believe the 95 and older are different then the 96 and newer.
I know the thread was here, I saved a link in my favorites, but it is no longer valid/active.
I just need to determine the correct set up. A company, XJ Armor, sells a set up, but they are not too dependable and the cost is a bit high.
Here's what I wrote in a post back in April:
I did the splicing thing. Works great, $15 worth of materials. 4-prong relay mounted near battery: prong #30 to battery (+) w/30 amp fusible link, prong #85 grounded to frame, prong #87 to fan splicing connector on (+) white wire on aux fan, and prong #86 to toggle switch. Ground toggle to metal under dash, run toggle (+) to under dash light (+) wire for lighted toggles and you're done. Best thing about it is you don't have to cut any existing wires. Fan goes on via ecu or manually via switch.
I run this and it allows me to manually turn on the fan or if I forget :-(, then allows the ECU to turn it on as programmed (218*, A/C on, or Defroster on). I have a '96 XJ country.
In my 1990, I just ran a power source from the fuse box out the the relay for the fan. Itll still turn on when its supposed to automatically. And I have control, a lot easier than what you guys are coming up with.
Here's what I wrote in a post back in April:
I did the splicing thing. Works great, $15 worth of materials. 4-prong relay mounted near battery: prong #30 to battery (+) w/30 amp fusible link, prong #85 grounded to frame, prong #87 to fan splicing connector on (+) white wire on aux fan, and prong #86 to toggle switch. Ground toggle to metal under dash, run toggle (+) to under dash light (+) wire for lighted toggles and you're done. Best thing about it is you don't have to cut any existing wires. Fan goes on via ecu or manually via switch.
I run this and it allows me to manually turn on the fan or if I forget :-(, then allows the ECU to turn it on as programmed (218*, A/C on, or Defroster on). I have a '96 XJ country.
Thank you. I think this is the thread I was looking for. You do not feel that a diode, to keep back feed to the ECU, is needed? That was another part of the discussion at the time. I remember someone suggesting it and they said the part was from Radio Shack.
Thank you. I think this is the thread I was looking for. You do not feel that a diode, to keep back feed to the ECU, is needed? That was another part of the discussion at the time. I remember someone suggesting it and they said the part was from Radio Shack.
XJ4Play, I've been running this setup for a couple of years now. I'm not much of an electrician, but I use the fan toggle pretty often and it's been a very reliable setup without the diode. I use a separate relay for my offroad lights and they've run reliably as well. Jeep runs excellent, too. No signs of feedback to the ECU.
I installed a diode in mine cos I'm anal about electrical stuff and because it all comes off a 6 switch panel, get one from an rv palce gut the power wire and then jst feed into it.
