Hubie

Hi,

I've searched the forums and can't find this issue solved.

I just bought this Jeep wholesale, its a 99 Sport, 4.0/auto; bone stock Cherokee. My big issue right now is no blower at any speed. I've checked the BMResistor; it's good. Swapped the Blower Motor Relay with the Starter Relay, still starts, still no blower motor at any speed. I have 12 vdc at the Fan Controller in the dash, but only on one pin, 2nd from bottom, Light Green wire. No power at the blower motor at all. I've done continuity checks on the wires from the fan switch to the blower motor resistor and they all checked out good.

Some other stuff that is wrong with this Jeep that might be related but probably is not: Rear Window Wiper, Rear Window Defrost both inop. Blinkers did not work at all when I picked it up, only left hazards. Replaced the blinker relay, now I have blinkers only when I depress the brake pedal (bad ground?) and hazards as they are supposed to. I have not been able to pull the multifunction switch yet to check that. Headlights, taillights, clearance lights and brake lights (all three) work fine.

Some previous owner had tapped into about 8 wires in the steering column wire harness (remote start system?), but I could not find any broken wires there, but they did a really crappy job of tying in to the harness.

ANY help or advice you can provide would be great. Any idea where I can find a functional layout of the fan control ****? I can use my meter to see if it is switching correctly. Any idea which of those fan speed control wires should be at 12vdc with the ignition on?

Thank You,

Joe

CCKen

Here's your HVAC Blower circuit.

I recommend that you pull the climate control panel and read each of the four switch contacts inside the control panel at connector C1, using pin 1 as your meter ground. The C1 connector is numbered. Other than this, you can use the schematic to find your way around the circuit.

You may want to detach the vacuum tube harness from the control panel at the quick disconnect (not at the control panel, like in the attached pic) behind the glove box if you want to completely remove the control panel from the dash (see pic).





Quick disconnect.

CCKen

Here's the Junction Block fuse guide and layout if you want to chase rear wiper and defrost issues. And other circuit issues that are powered from the JB.

Hubie

Thanks Ken. I'll get out there and start hunting some more. Once I find it, I'll be sure to post the problem child.

PocketsEmpty

CCKen, the electrical sorcerer.

Have you tried jumping the blower motor directly to make sure it runs? Have you removed the PO's wiring from the steering column?

Hubie

I can't get my fat hands in there to jump power directly to the blower motor, I could barely get the connector off to read it. No 12V there so I am expecting something else entirely right now. I have removed the PO's cruddy wiring, no breaks, but I had to do a lot of heat shrink and taping to get it all secure again. I think some people believe they are invincible and immune to fire. *sigh*

Hubie

Ken,

Thanks for the data. With what you provided, I've narrowed down that I don't have any power at the blower motor relay pin 30. There should be 12volts there. So, now I need to tear apart more of the dash and look at the connectors between the power distribution block in the engine bay and the blower motor resistor. I took readings in the bay and have 12V at the fuse on the inside leg and no continuity between the blower motor resistor and the other side of that 40 amp fuse. Must be an open somewhere, because it is reading infinity to ground too.

Thanks again, getting closer. Now if my paying job would stop getting int he way of my troubleshooting......

CCKen

Did you check continuity of all the blower selection pins on the climate control panel (connector C1, pins 2, 3, 4, and 5 to pin 1)?

CCKen

.

Hubie

So the latest.

Pin 30 at the Relay does not have power. I've used the drawings to figure out that this power goes from the 40amp fused PDC to the relay via C100 and C201. I have not managed to get C100 off yet. I loosened the bolt but could not get the plug out. Too cold and rainy today, I'll try again on Monday.

CCKen

Do you hve power at C209, pin 8? If you do you can rule out C100 and C201.

Hubie

I'll check that Ken. Thanks. had to work all day today, so didn't have any time to fiddle with my meter.

Hubie

Ken,

I could not see any numbers on C209, if there are any. By looking at the diagram you provided, pin 8 should be in the middle on the side nearest to the connecter locking clip?

The ONLY pin in C209 that has power is the red wire/green stripe, I believe this is pin #3 (middle pin opposite from the locking clip). It has 12vdc with the ignition on or off. Always hot. The light green wire does not have any power, ignition on or off.

If C201 is the big bugger to the right of the steering column, maybe I should pull that and look for power? C201 is grey with a bolted connector?

Sooo damn cold here, it's making troubleshooting a real pain. I need to do my front brakes too. I'd build a garage but the house lot is too small....

CCKen

There's a pinout of C209 on that schematic, next to the photo of C209, it shows the location of the pins.

"The ONLY pin in C209 that has power is the red wire/green stripe". This is pin 8. It is power from fuse 6 (40 Amp) in the PDC to pin 30 on the relay connector. It will always be hot off the battery. You have power to the relay.

You will need to check for power at C209, pin 9, with the ignition switch to RUN. This is power from fuse 25 in the JB to pin 86 of the relay to the relay control coil. Pin 10 of C209 is the ground circuit from pin 85 of the relay. You can use an Ohmmeter to check for continuity to ground from pin 10 to a spot on the dash structure. Without power from fuse 25 and/or without continuity to ground the relay won't activate (immediately when key is turned to RUN) and won't won't transfer power from fuse 6 in the PDC to the blower.

Hubie

I'll go check that now. Why would I not be able to read the 12vdc at pin 30 of the relay socket? Thanks, Joe