Odd electrical issue - Starts strong/dim lights/interior cutout/headlights ok

bdsmail

Original poster
Member
Mar 30, 2012
4
Sorry for the odd title, but I'm a big believer in helping out future searchers. :thumbsup:

I have one odd electrical situation that I am hoping has happened before to a GMTer. I took my car in for brakes and an annoying belt/pulley squeal, and my mechanic replaced my brake pads and rotors up front and pads only in the rear (69,000 on the original rotors for this heavy vehicle... pretty good to me). He also replaced my idler pulley for the serpentine belt as the bearings were shot and replaced my a/c belt. No problem.

That day I noticed the radio flicker (model with navigation/touchscreen ). Thinking it was simply a shadow or my shitty vision getting worse I didn't think much of it. Over the next few days I noticed it a few more times and started to piece together that something was up. Driving around last weekend, my entire electrical system inside only cut out - the engine was running perfectly as were the headlights, turn signals, and flashers. I'm assuming the brake lights are fine too but obviously I can't tell for sure. No power to the windows, radio or dash lights. Then everything came back on, my radio said Delphi as if I just connected the battery and the climate control came on with a garbage disposal-like noise which I assume is the actuator motor. Multiple dash lights were on, and my info center said multiple messages like Stabilitrak off, Service Brake System, Service tire Monitor, You're an ass how could you do this to me, etc. Thinking it had to be related to my prior service I went back to my mechanic. He said it sounded like a dirty ground or loose connection which made sense to me since it progressively got worse.

He tested the battery and while running measured over 15 volts coming from the alternator. When he triggered the load switch on the tester the interior lights did their magic yet again, this time with predictable results - every single time it was put under load the dash lights and tone went crazy. He suggested replacing the alternator but didn't have much more of a guess. I'm thinking it's something a little more detailed (but not necessarily difficult) since the battery is charging fine and starts perfectly. I went to Advance for a second test and it did the same thing. So, here are my symptoms:

  1. Starts absolutely fine every morning
  2. Runs strong
  3. Seems to be BOTH random and cause-able - the electrical cut out once when my fiance pushed the window down switch on the passenger side
  4. The entry lights (reverse lights) and dome lights are dim when I unlock and get into the car as if a dead or drained battery, but again it starts up just fine
  5. Alternator is putting out 15+ volts
  6. Testing with load produced the issues 8 out of 8 times
  7. XM radio cut out, navigation cut out, but FM radio works while the unit has power. Have not lost any presets, but the clock does reset to 12:00.
  8. "Reset" the computer by pulling the negative battery terminal for about 5 hours - why not, but had no effect
  9. Key has been stuck in the ignition since no power - once dash/interior comes back to life it comes out just fine

I have read about the key stuck in the ignition bit and if that is the issue... replacing that thing on the saab with the key in the middle of the car could be a tricky one. Anybody have a writeup on that by chance?
Thanks in advance.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The ignition switch contact assembly is notorious for going bad in other vehicles, but I have no idea how the Saab unit was designed.

Your symptoms all point to a loose megafuse connection, which feeds the rear fuse block from the front. Check the connections.

Where precisely are they connecting this load tester?

megafuse1-orig.jpg
 

bdsmail

Original poster
Member
Mar 30, 2012
4
Thanks Roadie, and thanks for the pic. I figure you have this on hand from similar issues, ha. Both tests were done at the battery. Think I should I get another one back at the rear block?

I will check out the megafuse in a few hours and post back.
 

The_Roadie

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Member
Nov 19, 2011
9,957
Portland, OR
I think that photoshop is about six years old now and I've posted it 100 times. Mostly it's goofballs who use the megafuse studs for a jump start, because the GM idiot designers used RED and BLACK wires for studs that BOTH have 12V on them. The manual, or course says to jump elsewhere, but the battery cover thwarts most folks who give up too easily when they need to clip on their $5.98 Walmart jumper cables. Yes, check the tightness of the rear fuse block feed stud also.

Also run a battery load test with the engine off. Could be a bad battery.
 

bdsmail

Original poster
Member
Mar 30, 2012
4
Thanks for the advice, will check out. Considering the battery is original and around 6 years old anyway I wouldn't be surprised if it's toast. Question though - is that a 150amp replacement fuse I see for a 125amp original?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Yes, it's the only one I could find outside the dealer network 6 years ago. Nowadays they have many values at the aftermarket parts stores because it's not such a rare part. Don't worry, I'm an electrical engineer and I don't plan on blowing my main fuse any time, and I don't have 5000W of audio gear running off the rear fuse block anyway.
 

RayVoy

Member
Nov 20, 2011
939
Bill is right, if definitely is a problem with the power going to the rear fuse panel.

He is talking about the power (12volt) lead, you might also have a problem with the ground leads for the rear panel, or perhaps a problem within the panel.

There is a ground connection near the panel, and a second one under the middle of the dash, just lift the top of the carpet to find it.
 

bdsmail

Original poster
Member
Mar 30, 2012
4
Good news (1): It's fixed
Good news (2): It looks like GM smartened up and finally used two red cables on MY2007 at least
Bad news: I don't know why or how this happened

See attached. My megafuse was literally sitting on top of the bolt drawing power from the battery instead of being bolted down underneath it. I have never touched it before and I have no idea how it got like that, you can even see where the plastic has been melting from the heat and sparking (I'm assuming a bit there, Bill you'd probably know best). I did originally get the car with 12,000 miles on it so maybe someone connected a amp power cable or something pre-me but since everything else was stock I doubt it. Could it have come from the factory like this?

Anyway, a pair of pliers and about 5 minutes in my work's parking lot and my problems were solved. In fact, my drivers side window that had been slowing down (which I attributed to an aging motor and/or the window lift needing greasing) now works like new. So very odd. Thanks Bill and Ray for your help.

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The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I love it when I issue a diagnosis and the patient doesn't die. Ray and I have worked together for years. :biggrin:

houseteam2.jpg


I absolutely can't see this being a factory issue. Previous owner was an idiot and removed something in a hurry. The heat comes from the high resistance - for the slow window motor, for instance, whatever energy wasn't going into moving the window was being dissipated as heat at the bad connection. At least they didn't steal the fastener on you. :hissyfit:
 

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