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Robert R
Robert R, ASE Certified Master
Category: Jeep
Satisfied Customers: 3992
Experience:  ASE Master Certified, Chrysler Certified
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2008 Jeep grand cherokee Overland. Door locks dont work. 20A

Customer Question

2008 Jeep grand cherokee Overland.
Door locks dont work. 20A fuse keeps blowing. Seems only to blow on the lock signal and not the unlock signal. My son said this was preceded by a rear passenger door open alarm but not sure if its related. I disconnected the rear passenger door at pillar but still blows fuses. Could it be a faulty lock command relay? If so where is it locatied?
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Customer: yes
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Customer: previous message
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Submitted: 7 months ago.
Category: Jeep
Customer: replied 7 months ago.
When I hit the lock button, I hear the relays click, even after the fuse is blown, if that matters.I see that the lock relay is in an integrated circuit junction box. Im not sure if this is my next move, to replace this unit, there are used ones for $50, new ones are $169.
Expert:  Robert R replied 7 months ago.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 28+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

I would start at that passenger rear door that is setting the door open alarm. The door ajar switch as well as the door lock for the right rear door is integrated into the door latch assembly. I'd start by checking the wiring to the affected door. Pull the rubber boot loose that goes between the door and the body of the vehicle. You may find some cut wires inside there. Have a look and post back any results...

Thank you,

Robert

Customer: replied 7 months ago.
I did that first I disconnected that already as I had noted. It still blows the fuse.
Expert:  Robert R replied 7 months ago.

Sorry, missed that.

Continue by disconnecting each door at the pillar. Post back the results.

Customer: replied 7 months ago.
That is difficult to do as the front doors have to be accessed by removing front fender.
Expert:  Robert R replied 7 months ago.

You should be able to access the connectors by just opening the front doors all the way. Use a pocket screwdriver to get behind the rubber boot to disengage at least 2 of the retaining clips, once that is done, you should be able to get to the connector.. Removal of the fenders is not necessary to access the connectors..

Keep me posted...

Thank you,

Robert

Customer: replied 7 months ago.
Golfing. Will try tomorrow.
Expert:  Robert R replied 7 months ago.

No problem....

For now, here is a pic showing the boot on the passenger side. Yours should look similar.. See the pic for info.

Rubber boot--->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 7 months ago.
Ok. All five doors disconnected and remote still blows fuse at lock command. Not unlock command. When I touch the junction box I can definitely feel the relay click on the unlock command. On the lock command I do not feel like click. There is a audible click away from the junction box but I think this may be the horn relay as the horn sounds when you press the lock command. Am I wrong in thinking this is a lock bad relay at the junction box?
Customer: replied 7 months ago.
Can I reconnect doors? It's going by to rain soon
Expert:  Robert R replied 7 months ago.

Ok, Sorry about the delay, was offline.

Ok, now that eliminates all the door wiring.

Let me do a bit more research. Go ahead and reconnect the doors. I'll be with you asap..

Thank you,

Robert

Expert:  Robert R replied 7 months ago.

Ok, after research it does appear that the door lock and unlock relays are internal to the Junction Block. At this time, I suspect that you in fact have a internal problem with the Junction Block. The Junction block is also the internal fuse panel under the dash driver area knee bolster. Remove this panel to see fuses, there are some relays in the back of the junction block but the ones we need to are internal and cannot be replaced.

Here is a pic of fuse and relay locations, note that the relays in question are not replacable:

--->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 7 months ago.
They are on back order. I purchased a salvage on eBay. Hope it works. Thanks.
Expert:  Robert R replied 7 months ago.

Sounds good, I'll be here in case you have additional questions after installing the JB.

Keep me posted...

Thank you,

Robert

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Customer: replied 7 months ago.
Ok. Changed the junction/relay/fuse module. No change. Still blows fuse on lock command.
Expert:  Robert R replied 7 months ago.

Ok, now try by snipping the light green/light blue wire a couple inches away from the Junction Block C3 40way connector. This is the door lock output from the Junction Block. Snip it in an easy to access place so that you can solder the wire back together after testing...

We need to see if the fuse still blows when you hit the lock button. Keep me posted.

Here is a wiring diagram and a connector pin chart for this connector. Match the connector to find the correct connector and verify that you are on the correct pin. Pin 36 should be the correct wire...

Wiring Diagram--->> Click Here to view <<---

JB C3 connector--->> Click Here to view <<---

Post back the results and we can go from there...

Thank you,

Robert

Expert:  Robert R replied 7 months ago.

Here is a location view of the Junction Block C3 Connector.

--->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert