2011 LR4 Rear Climate control not working

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
I?m in need of some help. I?ve searched the forum and I?ve tried all the suggested diagnostic tactics. The rear climate system in my 2011 LR4 Isn?t working. The front works fine. I?ve replaced the rear blower control module and that didn?t solve the problem. I?ve checked and replaced all the fuses, fusible links and relays that involve the complete A/C system. I have also bench tested the blower motor and it works fine. When I turn on the rear climate using either the button in the front or the ones in the headliner in the back, I can hear clicking noises both near the rear blower motor and I can hear the relay in the fuse box in the engine bay clicking on but the blower motor still won?t turn on. I?ve put the controls on full blast and tested the voltage at the blower motor plug and shows that I?m not getting power to my blower motor. This was both before and after I replaced the blower module with a brand new one from an LR dealership. I?m hitting a road block as to where else to check and what else to look for, is there anyone that could maybe give me ideas of what else to check or who knows what might be going on? Any help is greatly appreciated
 

jymmiejamz

Well-known member
Dec 5, 2004
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Los Angeles, Ca
What is the voltage reading of pin 6 (with everything plugged in, engine running, front and rear climate on) at the rear climate control interface connector? It is one of the red wires.
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
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Los Angeles, Ca
Also, put your volt meter leads on the two parallel pins (pin 86 and 85, you can google a picture, the relay is probably a standard 4 pin relay) for the rear blower relay when the fan should be running. I want to see that the relay is actually getting a signal to power the blower. Also check pin 30 where that relay plugs in, it should be battery voltage.
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Thank you very much for your response. I’ve stepped away for a little bit and will report those voltage readings back to you as soon as I have them,
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Alright, I put it all back together as I needed the car, but I’ll pull it all apart again and test all the voltages and report back to you and see what you think. Can you specify what you mean by the rear climate control interface connector?
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Across Pin 85 and 86 I get a voltage of 14.63, across pin 30 and ground i get 14.7v. On the blower control module between the black and red wire I get 2.144v and then between the green and ground I get 2.144V as wel. This is all with the car running and the controls on and on full setting. And pin 6 on the rear climate interface gives me nothing
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
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Los Angeles, Ca
Either I was looking at a different wiring diagram, or I typed the wrong pin number. I meant to type pin 2 at the rear interface. Sorry for the confusion.
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
That's good. That is the communications line from the Climate control module to the rear controls. If it weren't communicating it would be stuck at 12V.

Ohh ok, so would that tell me that it?s something between the rear interface and the blower motor? So when I turn the blower speed knob from the off position to any position I hear a clicking noise near the rear blower motor. But when checking the voltage on the blower motor pins there?s nothing
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
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Los Angeles, Ca
Just to back up for a minute, do you have power on the white wire at the blower motor? We know that the relay for the rear blower has power going to it, we know that the relay is being triggered by the rear climate control interface since you have power across those pins of the relay. Now lets make sure that power is actually getting to the blower.
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Just to back up for a minute, do you have power on the white wire at the blower motor? We know that the relay for the rear blower has power going to it, we know that the relay is being triggered by the rear climate control interface since you have power across those pins of the relay. Now lets make sure that power is actually getting to the blower.

No power to the rear blower motor, nothing at all
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Just to back up for a minute, do you have power on the white wire at the blower motor? We know that the relay for the rear blower has power going to it, we know that the relay is being triggered by the rear climate control interface since you have power across those pins of the relay. Now lets make sure that power is actually getting to the blower.

Thank you for all your help! Do you have any idea where else I can look Since there?s no power to the rear blower leads?
 

jymmiejamz

Well-known member
Dec 5, 2004
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Los Angeles, Ca
Thank you for all your help! Do you have any idea where else I can look Since there?s no power to the rear blower leads?

Sorry, forgot to reply!

Just to be clear, you were checking for power at the blower motor with one lead on an actual ground? the reason I ask is that the blower motor speed is pulse width modulated on the ground side. Whenever the relay is energised you should have full battery voltage at the blower, but the ground is pulsed to determine the blower speed.

Assuming you don't have power to the blower, next check to see if you have power at connector C0839S at pin 4.



The next connector in line is behind the central junction box and will be a bitch to get to. If you don't have power coming to the connector I listed, try running an external power wire to the blower straight from the battery (with a fuse). Connect it to the white wire on the blower as that is the power (the ground is the red wire oddly enough),
 

Zavanio

Member
Jun 29, 2017
14
0
Oviedo, FL
Sorry, forgot to reply!

Just to be clear, you were checking for power at the blower motor with one lead on an actual ground? the reason I ask is that the blower motor speed is pulse width modulated on the ground side. Whenever the relay is energised you should have full battery voltage at the blower, but the ground is pulsed to determine the blower speed.

Assuming you don't have power to the blower, next check to see if you have power at connector C0839S at pin 4.



The next connector in line is behind the central junction box and will be a bitch to get to. If you don't have power coming to the connector I listed, try running an external power wire to the blower straight from the battery (with a fuse). Connect it to the white wire on the blower as that is the power (the ground is the red wire oddly enough),
Absolutely no need to apologize. So I checked and I have no power to pin 4 of the listed connector. I connected power from the fused 12v auxiliary plug in the side to the white wire on the blower and now the blower is working and everything works as it should. Would the easiest solution then be to run a new power wire from the battery to the rear? Or do you have an idea where the fault might be then?

Again, thank you very much for all your help I greatly appreciate it!
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
35
Los Angeles, Ca
There is only one other connector in between and that is the one behind the CJB. It is probably worth taking a look to see if you can access it. If you can, see if you have power on pin 24 of connector C2244L/C2242L. If you do, then that means there is a problem on the interior side of the harness. If you don't, the problem is between the engine compartment fuse box and that connector. If you ever had a water leak it is possible there is corrosion in that connector, so it is probably worth checking out.



Your other option is to just run an overlay wire from the fuse box to the blower. Either way, you're probably going to have to overlay part of the harness unless you find the break in the wire.