Help with 2002 Ford Ranger blower motor

[sam_sam_sam]

Re: Help with 2002 Ford Ranger blower motor

https://www.aliexpress.com/item/1005004469418085.html

I would second this as a possible replacement controller for the resistor network

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

The only thing that can cause this problem is broken connections between the switch and the resistor block. NOTHING ELSE. it is the switch that shorts the appropriate resistor to ground so if you switch to medium high and the speed does not change and you replaced the switch etc, the only thing left is the wires and connections between the switch and the resistor block.

The mystery continues

I turned on the truck, and put the fan on low. I touched the Yellow/Red wire to the black wire under the hood, and nothing changed. It kept blowing on Low

Then, with the ground under the hood still disconnected, I ran through the settings, and it STILL WAS RUNNING ON LOW. The ground wire coming off the resistor block DISCONNECTED.

I turned everything off, and unplugged the connector from the resistor block I then took the plug from out of the cab switch, and checked continuity and resistance between all 4 connections. All four wires showed continuity and minimal resistance (1-2 Ohms)

So there is no break between the wires going from the switch to the resistor block.

I happened to have a spare resistor lock (it came with my new plug), so I swapped it out. No change, Low, Med Lo and Med Hi work as Low, Max works on Max.


So at this point we have a brand new switch, TWO brand new resistor blocks, a brand new resistor plug, continuity between all the wires, and confirmed power to the motor, and (supposedly) confirmed connection to both grounds. But it STILL doesn't work.

Is this beyond hope?

[diif]

Re: Help with 2002 Ford Ranger blower motor

Have you checked for continuity between the four wires ?

[petehall347]

Re: Help with 2002 Ford Ranger blower motor

have you tested the switch and wiring by unplugging at the fan and checking continuity at different switch positions ?

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

Have you checked for continuity between the four wires ?

have you tested the switch and wiring by unplugging at the fan and checking continuity at different switch positions ?

I have checked continuity between the switch and the resistor plug. I have checked resistance at the resistor block between the Med Lo and Ground and Med Hi and ground when those fan speeds are selected, I will try them out again. I will check continuity between the wires


One thing I noticed when I was working on something totally unrelated is that there looks to be a broken ground strap, underneath the passenger side door underneath the truck. I see the terminals but the strap is torn. I wonder if that is related to G201, and if the only ground that is actually on place is G105, which is always Low?

[redwire]

Re: Help with 2002 Ford Ranger blower motor

That is pretty tough, rated 40A using 5-6 power mosfets (plus big diode) IRF3205 on heatsinks.
The common smaller 10-20A model has audible 13kHz PWM so it would squeal and drive me nuts, the big guy is ok at 25kHz.

[sam_sam_sam]

Re: Help with 2002 Ford Ranger blower motor

One thing I noticed when I was working on something totally unrelated is that there looks to be a broken ground strap, underneath the passenger side door underneath the truck. I see the terminals but the strap is torn. I wonder if that is related to G201, and if the only ground that is actually on place is G105, which is always Low?

Could be one test that I do if I think that it might be ground terminal related is that I run a wire from the negative side of the battery to the device that is having an issue and see if the device works correctly after doing this

I have a car that has an issue with the turn signal light flashing faster on the left side and normal on the right side when putting a wire from the negative side of the battery to the light bulb socket it works normal but as soon as I remove it it starts flashing very quickly again but I also have an issue with the headlights on this side as well but it is a socket issue with the headlights but I have not had time to figure out where the ground issue is

But it has not gotten worse and sense it is still working but when the holidays are here and I have time off from work I might try to find out where I have a bad ground terminal is at

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

https://www.aliexpress.com/item/1005004469418085.html

That has 4 terminals on it, Which wires would I hook up?

Could be one test that I do if I think that it might be ground terminal related is that I run a wire from the negative side of the battery to the device that is having an issue and see if the device works correctly after doing this

So I would connect the black wire coming from the resistor block directly to the negative of the battery and leave the colored wires connected, and if the ground is the issue it should work by changing the selection on the cab switch?

[stj]

Re: Help with 2002 Ford Ranger blower motor

2 terminals to the fan, 2 terminals are the power input

[sam_sam_sam]

Re: Help with 2002 Ford Ranger blower motor

That has 4 terminals on it, Which wires would I hook up?



So I would connect the black wire coming from the resistor block directly to the negative of the battery and leave the colored wires connected, and if the ground is the issue it should work by changing the selection on the cab switch?

You need to which wire is the ground terminal for the motor this is very important for you to do this test

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

2 terminals to the fan, 2 terminals are the power input

Looking at the schematic, at the cab switch, I have an Orange/Black wire that is the 12V line. when the vent selector switch (separate switch) is on any position except off, it always sends 12V to that line. That line is what feeds the power to the fan. So that would be on one terminal, but which other wire would I use? There are only 4 wires by the cab switch, the 12V line, and the three speed settings (one of which just goes to a ground)

You need to which wire is the ground terminal for the motor this is very important for you to do this test

Shorting the Yellow/Red wire to ground should make the fan run in Med-Hi speed, so wouldn't I connect the Yellow Red Wire coming from the resistor block to the negative battery terminal to perform that test?

[redwire]

Re: Help with 2002 Ford Ranger blower motor

I have learned to check the ground connections - because sometimes they combine grounds into one lug or screw which causes really strange things to happen when that disconnects from ground. If this is your case, you might have some other accessory sharing or providing the ground and interacting with the blower motor switch. I would go after G201 (right kick panel) and make sure it's solid.

The truck should have two main grounds, battery(-) to engine block and another wire/flat braid to the chassis (i.e. fender). GM runs a flat braid from the block to the firewall.
Without the chassis grounded right you get strange things like dashboard lamps coming on dim, tail lights doing other strange things as well.

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

I have learned to check the ground connections - because sometimes they combine grounds into one lug or screw which causes really strange things to happen when that disconnects from ground. If this is your case, you might have some other accessory sharing or providing the ground and interacting with the blower motor switch. I would go after G201 (right kick panel) and make sure it's solid.

The truck should have two main grounds, battery(-) to engine block and another wire/flat braid to the chassis (i.e. fender). GM runs a flat braid from the block to the firewall.
Without the chassis grounded right you get strange things like dashboard lamps coming on dim, tail lights doing other strange things as well.

The chassis ground is rotted away. I don't know what they consider the "right kick panel" is that inside the cab?

[redwire]

Re: Help with 2002 Ford Ranger blower motor

I think it's inside the right kick panel. Looks like it's on top of G203.
DON'T disconnect the ground without disconnecting the battery- G203 might be for the ECU.

[sam_sam_sam]

Re: Help with 2002 Ford Ranger blower motor

Then add wire to the terminal and go to a better grounding point
This is good point about the ECU disconnect from the battery negative when doing the grounding cable

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

Then add wire to the terminal and go to a better grounding point
This is good point about the ECU disconnect from the battery negative when doing the grounding cable

Which terminal?

Here is a picture I mocked up so we can make sure we are referring to the same things. When I tested it, I had 4 & 8 connected, 3& 7 connected, and then 1 & 2 connected and the fan did NOT run in Med Hi mode.

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

I think it's inside the right kick panel. Looks like it's on top of G203.
DON'T disconnect the ground without disconnecting the battery- G203 might be for the ECU.

Where are you getting these pictures they are awesome

I will disconnect the negative battery terminal and then inspect those grounds. I will also replace that rotted ground underneath the chassis

[SluggerB]

Re: Help with 2002 Ford Ranger blower motor

Ground is the chassis or battery negative, I have no idea what that metal tube is. You need to read the resistance as the beep is meaningless as it can beep between 0Ω and likely 200Ω depending on the meter.
For the test connect the ground wire to pin 3 on the resistor network or just connect a wire between pin 2 and 3 on the resistor network, this should increase the speed.
The switch in the cab can be on any speed but High for the test
If you connect a wire to pin2 (ground) on the resistor network, and the other end to either pin 1, medium low or pin 3, medium high, if you connect to pin 4 the fan will run at high speed.

Since this did not work, what else could it be? I looked back and no longer suspect the grounds since Low and High work, and each uses 1 of the 2 grounds. The resistor block simply ignores the Med Lo and Med Hi wires, despite them being connected. I was able to test for continuity for the Med Lo and Med Hi wires between the cab switch and the wires going to the resistor plug and they all showed continuity. I do not know how to test for resistance because people are telling me to go to test locations that I do not understand.

[R_J]

Re: Help with 2002 Ford Ranger blower motor

All the switch does is short part of the resistor block to ground. If the wires are good and the resistor block is good, then your switch is bad

More research tells me the plug going into the Resistor block often gets corroded and faulty, so I change that

If you changed the plug, you already cut the wires and spliced them, so leave the orange/black wire connected to the resistor block, as well as the black. now remove the splice in the light green/white wire and connect the lead that goes to the resistor block to ground. If the speed does not change the connection between the plug and the resistor block can not be any good.

[stj]

Re: Help with 2002 Ford Ranger blower motor

why not test by putting a jumpwire into the switch connector?