1996 XJ 242, 360,000 miles.
At the junk yard yesterday while I was taking parts off a 1995 XJ I remembered I don't have high on my blower motor, so I snagged the resistor module from the 1995 also. I replaced it once around 2003. Back then it didn't solve my problem, had to get the switch rebuilt.

This time I don't think it is my problem either, since the only setting that doesn't work is high. From this wiring diagram it looks like high completely bypasses the resistors.




Anybody know if this is the right switch to replace?
https://www.oreillyauto.com/detail/b...r+switch&pos=1

 

I don't know if that's the right switch, but have you probed the back to see if you're getting voltage at the back of the switch (in high, plugged in)? Does sound like a fried switch to me though.

 

Works on the other settings.

 

I can confirm the high setting bypasses the resistors.

Mine still works on all speeds, but when I bypassed 3 lower speeds with relays,

Hi is still direct, and I couldnt find a wire to bypass (without tearing into the dash)

Not sure whether your switch is gone, but probably

I would be interested in your findings about the wire location for HI

I do not use this setting, 3 is good enough

Its only a matter of time before the Fan fries something in its current path for pre-update owners, unless you bypass with relays

 

If I am reading that wiring diagram right, high should be #2 on here and #5 not used.



Do you have a picture or diagram of the relay setup you made?

 

looks correct...they call out C242 (twice in the diagram)..but I couldnt find the connector or spice...its not close to the resistor pack as implied


What I did is run a fused 12V wire thru the firewall, and mounted 3 relays behind the PS kick panel, and made a little harness to run the resistor control wires to the relay input, and then back out to the resistor pack.

This way, each resistor has its own relay

there is no other way around the problem but a separate relay for each speed (problem cured on post-update with circuit re-design)

All reversible if I ever wished to...all the current flows thru the ignition switch for fan and headlights on pre-updates, unless relays are used

 

High does bypass the resistor completely so it's one of three things really.

1. High contact in the switch has burnt out
2. The connector on the back of the switch has melted and making bad contact on the high pin
3. There is a break or high resistance in the wire from the switch connector to the resistor connector

The best way to test this would be to pull the dash panel off, get at the connectors on the back of the heat selection, get access to the resitor connector and get testing with a multimeter with the fan set to high. If there is high resistance causing an issue, you'll find it much easier via a voltage drop on a live circuit. Just check your voltage on the input pin and output pin and look for drops.


I typed this out an hour or so ago then forgot to post so sorry if anything has been covered already.

 

You have just jogged my memory, and I think it went like this;

when I detached the correctly colored wire from the resistor pack (which you have pictured)...instead of the fan motor stop spinning on HI, it just kept buzzing away

I might be wrong, but thats my recollection.

would add another relay for HI, if I could easily find the right spot to intercept the wire, hence my interest

 

Which relays did you use? Have any pictures?

 

No pics...it looks dead stock..nothing to see!

I just bought a 4 pack of Bosch plastic 5 pin relays with holders $20, and placed them behind the inside kick panel

As I said, all relays are fed by a common power source from the engine bay, and my harness just plugs into the Jeep harness female spades, which trigger each relay,
and the output of the relevant relay goes to the appropriate resistor terminal

 

Just dug into dash. The high speed wire is fried (lowest pin on the switch). When I get some relays will try to fabricobble the fix together.

 

If you tinker with it again, you could get power from fuse 5, the 30 amp blower motor slot on the cabin fuse block.

edit: oops that still goes through the ignition switch

 

At least it never caught fire.

 

Looks like I am not getting out that cheap. I tried, I really tried to use Del City for this but shipping was killer. Four Song Chuan relays and a 4 way relay box over $50.
On Amazon, I have 4 true blue Bosch 5 pin mini relays and a no-name 6 relay box in cart, $37.75. Will get wire local and do that myself since so many of the Amazon sellers seem to be using 14 AWG when they should be using 10(?).
Anyway, will run the power with 10 AWG and switching 14 AWG. Will probably mount the box next to the fuse box under hood, add a 30A fuse to the stock fuse box and run it to the new box and then the wires through an existing firewall hole to connect into harness for motor.
All plans subject to change when they meet reality.

 

A couple of notes on what I did

its tricky to fit the relays in neatly behind the kick panel.

I considered affixing them, but in the end, I just lay each relay in there, along with the other wire harnesses and connectors

It would be even harder to get 4 relays in, but I think you could

I also deliberately ran a separate wire thru a grommet direct to the battery, which is labelled

this is so if someone in the future has an issue, including me, they can work easily work out that it is wired non-standard

What did you have to remove to access the switch (for HI) ?

30A is a lot to go thru the ignition switch, if it also has headlights, and other power draws added up