How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1523
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
Type Your Chevy Question Here...
Juan Crespo is online now
A new question is answered every 9 seconds

I have an 07 Yukon with some electrical issues. I was hoping

Customer Question

I have an 07 Yukon with some electrical issues. I was hoping you can tell me or show me a diagram with the i/p junction blocks terminals and there respective functions.
Submitted: 6 months ago.
Category: Chevy
Customer: replied 6 months ago.
I have a service 4wheel drive error on the dash and the check engine light is on. We pulled the codes and it has a lost communication with the transfer case control module. It also has 3 codes in the history...lost communication with body, engine, and transmission control modules. I found a technical service bulletin and think I may have narrow it down to a lose wire on the X1 connector of the I/p junction block. I have also been experience other symptoms as well, like the radio and/or dome, front door light, and dash lights don't shut off anymore when you exit the vehicle from any door (well Actually about every 20 door openings it will randomly work correctly.) I also hear a loud buzzing noise cycle on and off...I believe from the fuel pump. Sometimes the traction control light comes on and the vehicle looses acceleration. And sometimes the lift gate won't open and /or close.
Customer: replied 6 months ago.
paticularly terminal F3
Expert:  Juan Crespo replied 6 months ago.

Hi there.

Knowing what those code numbers are will help me gain some insight on how to best help you. Any chance of getting them from you?

Customer: replied 6 months ago.
Active: u0102
History: u0100 u0101 u0140
Expert:  Juan Crespo replied 6 months ago.

Thank you. Please give me a chance to review these codes. Be back in a bit...

Expert:  Juan Crespo replied 6 months ago.

OK. Since the BCM is the "boss module" and knowing there is a pattern of failure due to bad grounds, that's where I would start my diagnosis. Do you have access to a Tech-II or equivalent scan tool capable of communicating with the BCM?

Customer: replied 6 months ago.
I have a friend that will lend me one but he is not very experienced with it and wouldn't know how to diagnose it.
Expert:  Juan Crespo replied 6 months ago.

The advantage of using the scan tool is that you can wiggle the harness and tug on the connectors and see if values change on the display. The option would be to do a complete pin-out, but doing that wouldn't reveal loose or intermittently bad connections, or tell us whether or not we have a bad module.

Customer: replied 6 months ago.
Can you give me a diagram that tells what the terminals on the ip fuse block control?
Expert:  Juan Crespo replied 6 months ago.

I can probably get you the connector pin-out. Are there 4 connectors going to the one you're working on? Also, can I get the VIN?

Customer: replied 6 months ago.
3 on the front and 1 on the back. I need to know the one on the back
Expert:  Juan Crespo replied 6 months ago.

What about that VIN?

Customer: replied 6 months ago.
It's Connector X1
Expert:  Juan Crespo replied 6 months ago.

Well, there isn't much I can do without the VIN to look up the correct diagram. Any particular reason why you won't give me that information?

Expert:  Juan Crespo replied 6 months ago.

Man, I'm on your side, but you sure make it hard for me to try to help you. you see, without the VIN, I didn't know what the body style was or what engine and other features were in it, so I just went with what you gave me "2007 Yukon". I've attached the pin-out for connector X1.

Hope that helps you out.

Customer: replied 6 months ago.
Yeah MAN, easy, I thought I had sent to you like 3 answers ago.. This website is not exactly real time info. I submitted 3 answers in a row right after you asked me for the vin and apparently the 1st one didn't go through. No there is absolutely no reason why I would t give it to you.1GKFK13027R128109
Customer: replied 6 months ago.
Also got a broken phone and limited opportunities to check your responses
Expert:  Juan Crespo replied 6 months ago.

Like I said, I'm on your side and all I want to do is help you. As it happens to be, the pin-out I uploaded for you fits that VIN - 2007 GMC Yukon 4WD 4dr 1500 SLT 5.3L Flex Fuel.

Please let me know if there's anything else I can do.

Customer: replied 6 months ago.
I'm not seeing an F3 terminal. That is the one I am looking for info on
Expert:  Juan Crespo replied 6 months ago.

Please see attached graphics.