Hey all,

I have a 99.5 DII that the blower motor just stopped working on. I have replaced the resistor before, and it doesn't work on any speed, so I know it isn't that. I'm not getting power to either of the larger wires on the two relays next to the blower motor (the wires that would send power to the fan/resistor circuit), so I'm wondering if its the control module? Both relays have power going to only one terminal, and its the same terminal for both, I believe its the wires that are meant to close the relay. What should I tap with a test light to narrow this down? NO power at all to the blower motor.

 

UPDATE: Replaced the control unit with a known working one and still nothing. Swapped the fuse just to humo(u)r myself and that did nothing. Anybody have the wiring diagram for the blower motor so I can play "test the wires?"

 

You say you swapped the fuse, but you didn't mention which fuse number or if you had current there. Current runs from the battery to the engine compartment fuse box (by coolant reservoir), to fuse link #1 & #4, where it then runs to passenger compartment (panel under steering wheel), to fuse #7, from fuse #7 it goes to relays.

Other fuses that are tied into the heater system are fuse link #8 in engine compartment fuse box and fuse #31 in passenger fuse box...but these are primarily for the vent door motors...but worth checking.

Also, did you try jumping the relay to see if the motor ran?

Brian.

 

I swapped the fuse at position 7 in the cab. I used a test light from the main battery fuse back, and no fuses in the fan circuit have power after the 100A fuse at position 4 on the main block, including the defrost fuses. I have power on both sides of the position 4 fuse though. Jumped the blower motor so that is confirmed good.

 

If you have power on both sides of fuse #4 in the engine compartment, I'd then unbolt the fuse box housing and see if a connection has become loose or corroded. If they look good, follow the harness where it goes through the firewall, right under hood hinge passenger side, check to make sure the grommet hasn't been dislodged and wires are now rubbed through.

If everything looks good to that point, drop the drivers compartment fuse box and check for issues there on the backside, again, looking for loose/corroded connections. If you find no issues there, or no voltage at wire coming from outside source...then you possibly have a broken wire or chewed wire by a varmint. You could run your own jumper wire to pass. fuse box fuse #7 and see if everything works beyond there (heater motor).

Brian.

 

UPDATE: I admitted defeat on the diag for a while and just ran power to a switch for the fan until I figured out I could wire it straight because the HVAC controller closes the ground. Last weekend it decided not to start at all, no spark. I replaced the Crank Position Sensor and that didn't do it, but it would run if I jumped the two ignition fuses on the cabin fuse box. New/used fuse panel later, and it starts up fine, but also my fans (discovered later on that the rear fan had no power either) were working again as well.

TL;DR The cabin fuse boxes on D2's fall apart and mess with stuff.