NEED HELP No Electrical Power at all. (2008 Saab 9-7X Aero)

[citymunky]

I accidentally left my phone charger plugged into the cigarette lighter for over a month while my SUV sat unused. Not surprisingly, the battery was completely dead. I first tried jump-starting it with a portable jump pack and then with an older 120-amp plug-in charger/jump starter, but neither worked. I eventually replaced the battery with a new one.

After installing the new battery, I turned the key and the starter engaged for a split second. Immediately afterward, the entire vehicle lost electrical power—no dash lights, no ACC power, nothing. At the same time, the key became stuck in the ignition.

I started with the basics:

1. Verified battery connections were clean and tight.
2. Swapped relays.
3. Checked the 125-amp fuse with a multimeter (tested good, not OL).
4. Verified 12.5 volts between the battery and the underhood fuse box input, as well as across the 125-amp fuse.

After ruling out the obvious issues, I began tracing the circuit using the wiring diagrams.




According to the diagram, battery power (B+) feeds the underhood fuse box and then supplies Fuse 61 (IGN A1) and Fuse 16 (IGN B1).

• IGN A1 (Circuit ID 142) runs from fuse box connector pin B9 to ignition switch connector pin 2. Based on the diagram and wire color (red), I believe this circuit should have 12 volts at all times.
• IGN B1 (Circuit ID 342) runs from fuse box connector pin E5 to ignition switch connector pin 6 and should also be hot at all times.

I removed the ignition switch and checked the connector for voltage. Pin 2 (IGN A1) and pin 6 (IGN B1) both measured less than 1 volt.



I removed the ignition switch and checked the connector for voltage. Pin 2 (IGN A1) and pin 6 (IGN B1) both measured less than 1 volt.

Since those circuits were not receiving battery voltage, I suspected the fuse box. However, both Fuse 61 and Fuse 16 showed 12.5 volts on both sides of the fuse.

I then removed the fuse box and performed continuity checks:

• B9 to ignition switch pin 2: good continuity.
• E5 to ignition switch pin 6: good continuity.
• Fuse 61 to B9 through the fuse box: good continuity.
• Fuse 16 to E5 through the fuse box: good continuity.
• Continuity from the fuse box power input through the associated fuses also checked good.

At this point, I'm stumped. I can verify battery voltage all the way to the fuses, and continuity checks good from the fuse box to the ignition switch. Yet the ignition switch feed circuits only show about 1 volt.

Am I overlooking something? How can there be battery voltage at every point up to the fuses, continuity through the downstream wiring, but no usable voltage at the ignition switch?

 

[mrrsm]

Welcome to GMT Nation...

Following "First Principles"... KOEO... Locate your Fuse Box Panels(s) and using a DMM ...via the Pointy Ends of the Black & Red Leads... Check the Continuity of every single Fuse at their Test Contacts....WITHOUT REMOVING ANY FUSES BEFORE, DURING AND AFTER THIS TEST... that you can find and ONLY Replace any that are FUBAR. Then... Turn the Ignition Key "ON" ...and see what *Pops*.

If NOTHING Happens... Examine your Black Battery (-) Ground and Red Battery (+) Leads at the Engine Block Ground Locations and at the Starter Motor for any signs of GREEN (CuO2) Cupric Oxide Corrosion or Red (Fe2O3) Ferric - Oxide Rust Corrosion and REPLACE THEM.

Clean the contact surfaces down to GLEAMING and then apply a Dollop of Dielectric Grease and Re-Attach the Brand New Leads. Do NOT Over-Tighten the Fasteners! Turn the Ignition Key "ON" and see what *Pops*.

Make sure to Check the Engine Block Ground Wire attached to the Passenger Side REAR Head for installation at the Firewall. If BROKEN Off... The Engine WILL NOT START.

While wearing Clear Eye Protection, an N-95 Mask and M11 Nitrile Gloves... Use a Bright Flashlight and Look over the ENTIRE Under-Hood Wiring Harness for ANY signs of Vermin Nesting via the North American Deer Mouse or Squirrels that may carry the Deadly HANTA Virus (40% Fatality Rate once Inhaled or Ingested) hidden within their Dried Saliva, Desiccated Feces and Urine Deposits while searching for signs of Rodent Nests, Wire and Plastic Electrical Connector Depredation for indications of ANY Unexplained Non-Starting Electrical Conditions.

Look up Eric "O"s (SMA) South Main Auto Video for finding Chewed Wiring in the Undersides of the rear of a GM Truck where the Mice set up a hidden nest inside the back of the Fuse Box.