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2003 2500 Suburban Not Cranking

sbcathey

By sbcathey
in Ask A GM Technician

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sbcathey Enthusiast

sbcathey

Posted
Posted

This last Friday I was headed out of town and ran out of gas, and maybe burnt up the fuel pump. I'm not sure because when I put gas in the tank, it would not crank. The switch acts completely normal (all dash lights flashing, head light go out and come back on), but it never even tried to crank over. I do not hear the fuel pump run for two seconds when I turn the key to ON. The only other weird thing I have noticed is the transmission indicator light is not coming on. PRND21 is all lit but no indication of what gear it in. I really think this is one glitch, not two or three things happening all at one time.

 

Thanks

Scott

 

Oh yeah the first thing I did after everything went south last Friday was go buy a brand new battery

minibike132 Senior Enthusiast

minibike132

Posted
Posted

On the left (driver) side of the transmission where the shift lever is there are 2 connectors, one 4 terminal connector and a 7 terminal connector(the 7 terminal will only have 6 wires in it). Try to unplug these my bet is they will not unplug. This is the neutral saftey switch. If you can't see position on the dash chances are the crank circuit can't tell that you are in an ok gear to crank. Forget the fuel pump for now you have to get this thing cranking before you get all carried away on not having fuel, spark etc. Usually the glue inside these switches overheats and bleeds out into the connectors spreading the terminals. In the case that this happens the plugs are pretty hard to get out I usually use a heat gun for a few minutes to get the ball rolling then replace the switch and both connectors. If you can get them apart and you do not see any problems repost and we can go through some testing.

sbcathey Enthusiast

sbcathey

Posted
  • Author
Posted

Ok, I finally got some time to take a look at this. Yes the plug has glue in it, in fact both have some glue. I called and the switch is $49, but the seven plug connector is $108!!!!!! the four wire is $50. is that normal? I would like to know if this is like a wireing harness replacement or just pigtails I would need to shrink rap??? Is the switch bad or does it need to be replaced just because this rediculous glue. Is there anyway to get the glue out of the male or female connectors?

 

Thanks

minibike132 Senior Enthusiast

minibike132

Posted
Posted

Yea that sounds about right for the connectors. The connectors you will get are just pigtails that you would splice and heatshrink. You can try to clean out the old ones with something that will disolve glue. The approach of just cleaning them has never worked for me. I've tried removing terminals and using carb clean to disolve the glue then electrical contact cleaner to take off the residue then replaced only the terminal not the whole wire. This is a pretty labor intensive approach but has the best outcome because there isn't enough room to stagger 12 splices so if you go the splice route you end up with one huge ball of splices. Once the glue is in there it usually spreads out the physical connection part of the terminal. The glue film isn't the only problem. If you know how to remove terminals from the connector you could try that and clean everything up real good then carefully put tension back on the terminal. If you don't know how to do that I really don't know how to explain it without showing it. You do need the new sensor, once the glue gets melted on the original it is junk. Good luck keep us posted, Sounds like you are on the right track.

sbcathey Enthusiast

sbcathey

Posted
  • Author
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Well I put a new switch in with new connectors. It didn't change anything. Is there some more testing I need to do?

Scott

 

Also, I've read about a 20A ECM B fuse that breaks and causes the same symptoms, I dont remember seeing an ECM B fuse, am I missing it or is it named differently on a 2003?

sbcathey Enthusiast

sbcathey

Posted
  • Author
Posted

Ok, After another look under the hood PCM B 20A fuse was blown. I replaced it and the car started. Anyone have a clue where I need to look for the short?

Scott

sbcathey Enthusiast

sbcathey

Posted
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Ok now I think I have a handle on this thing. The PCM B supplies the Fuel pump, I heated up the fuelpump with running the truck low on gas, and if the fuel filter is dirty the pump would have to work harder and heat more. I think this is what popped that fuse. I drove it down to the gas station put 5 gals in it and drove to Checker got a filter and drove home about 10 miles with no fuses breaking. Now that the filter is replace I bet I don't have anymore trouble with it. Oh yeah I learned my lesson about running these things low on gas.

Scott

I cut the old filter open just for a visual, it looked pretty clogged to me.

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