96 Suburban 7.4L Will not turn over

[mikewe]

I have a 1996 GMC Suburban with a 7.4L engine (188K miles). When I turn the ignition key, the dash board lights up, the fuel pump makes noise, and nothing else happens. Prior to having this total failure, I had several occurences of turning the ignition key and having the same symptoms, however if I hold the ignition key in the start position for several seconds the engine would start (acting like once enough electrical current was flowing it would start). I had the battery checked after the first occurence, and it tested out ok and was fully charged (battery is several years old).

Also, I reseated the breakers and verified all fuse links in the fuse box under the hood and verified the voltage level at the box. Doubled checked that all wiring was either tight or connected. The ground connection next to the battery to the wheel well is tight. I am thinking that it is a grounding/wiring issue, not sure where to start. Could an OBD2 scanner help with this condition? Also any other thoughts or ideas would be of great help.

Over the last several years:
1) I have replaced the fuel pump twice, sender, and wiring harness to the pump.
2) Replaced the positive cable wiring between the battery and the computer/fuse box (Dealer recommended).
3) Replaced various hoses
4) Replaced the water pump

Issues I have once I resolve the starting issue are:
1) Low engine temprature/no heat - possible open thermostat
2) Leak in power steering/brake booster. Leaking on the power steering side. No gasket available, have to replace the entire part ($650 for the replacement part).
3) Right Side rear passenger door window only going down half way, lock is hard to operate. Saw several good posts on this one.
4) Rear AIR not cooling.
5) Right Side front passenger door sagging. Hinge pin is ok. Lifting the door shows the hinge is loose on the frame.

Any help with these issues would be greatly appreciated.

Thanks,

mikewe

[slothman6]

Ignition switch in steering column needs replacing....that would be my guess.