Suburban 2004 Electrical or Starter Diagnostic

2004 Suburban 1500 LS

In the past few days my wife has reported that a few times all the lights on the dashboard and control panel would flicker off and back on and the radio would be reset to 12. As if the battery had been disconnected. The car was still running and, other than the clock being reset, there didn’t seem to be any issues.

However, tonight I went out to start it and it wouldn’t turn over. No turning over. No noise. No nothing. I tried jumping it and it started right up. Let it run for awhile, then turned it off and tried immediately to turn it back on. Same deal. Absolutely no effect. No noise. No indication that I was doing anything other then turning the key in the ignition.

I got out my multimeter and checked the battery. 12.6 volts. I checked the ohms from the negative to the engine block. 0. So… battery and ground seemed good.

I jumped the car again and while it was running (after removing the jumper cables) I checked the battery again. 14.2. So… the alternator seemed to be charging the battery just fine.

But, I turned off the engine again and tried starting it again. Absolutely nothing. Tried jumping it again, immediately started up and ran as happy as a clam. At least until I turned it off.

What do you think might be the issue? What else should I check?

Check the terminal connections at the battery.



I wondered about that, but their is no corrosion at the terminals and the connections feel tight. Just in case, tomorrow I’ll take them off and make sure everything really is clean.

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The battery could have failed internally and still measure 12.6 volts. Especially if its internal resistance is very high.

Measure the battery voltage WHILE TRYING TO START THE ENGINE. If it drops much the battery has failed. You might even be able to do the same test by measuring the battery voltage while just turning the headlights on. Again, if the battery voltage drops much the battery has failed.

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I’d suggest load testing the battery… car parts places will do that for free…it may have a “surface” charge of 12.6v but fail a load test.

But also check the battery positive cable connector block on the driver’s corner of the engine (follow the battery lead) for corrosion. There are several cables bolted inside that red box.

Also, there are a couple of ground connections on the frame just under the drivers floorboard. They tend to get corroded. Clean those up as well. Or repair if needed.

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I’d also suspect a bad battery.

How old is the battery? If you don’t know and/or it’s been more than a few years, go ahead and replace the battery. It’s a good first step.

Another idea, starter motor problem. If solenoid contacts are “iffy”, could crank ok with higher voltages that you get when jump-starting, but not from just the single battery. Good idea with this symptom to ask shop to measure the voltages at the starter motor during attempted cranking. Both the B and S terminals should measure at least 10.5 volts, measured from terminal to starter case.

The battery cable bolts can measure 12.6 volts while the cables have a corroded, poor connection to the battery.

Well, I took the battery to O’Reilly and had them check it, it was fine. Hmm. Took it home and reinstalled it. Now the car is starting just fine. I have to assume one of the battery cables was the tiniest bit loose, though they both felt tight when I checked them before. Thanks for the suggestions everyone.

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Do the cable ends have a bright copper appearance?

The GM side mount battery cables are notorious for corroding under the rubber cover.


If you still have problems in the future with poor connections to the battery, I recommend replacing the cables.