GM-GMC: 1996 GMC Suburban Starting Problems, gmc suburban, radio fans

Question
Harry,

My 1996 Suburban suddenly refused to start with out jumping the battery. Battery voltage is 12.6 before starting and 14.4 while running. Once started it seems to run fine until you try to drive then it completely shuts down, and will not restart without jumping. When I turn the key there is clicking and various lights flickering. The strangest part is that the speedometer is pegged all the way to 100, and the car is sitting still.

After getting it started I tried flipping switches of anything electrical to see if there was a drain. Radio, fans, lights all seemed to work fine. When I hit the electronic 4 wheel drive buttons it allowed me to switch to 4 low/high, but once I hit the 2 wheel drive button it suddenly died.

About three days ago I changed the spark plugs - and the previous owner had the 4X4 electronic control module replaced about a year ago. The vehicle has 140,000 miles on it and has been maintained and serviced quite well. I have owned it 2-3 weeks and it had run great, except for a high speed miss (the reason I changed the spark plugs) It seemed to solve the problem until this. Alternator was also replaced about three years ago or 30,000 miles ago and the battery is new this year (less than 3 months old).

Thanks

Answer
Lance,

You probably have a bad ground connection (or more than one bad connection).

Remove and clean all the connections you can find.  Under the hood, under the vehicle (usually connected to the transmission), and under/behind the dash.

Remember that battery cable can corrode under their insulation, so replace any cables that look like a snake that has just swallowed a mouse (insulation that looks swollen).