Assuming the engine has not siezed, there is a short in the starter circuit. Probably the starter/solenoid, but you can verify. Disconnect the negative battery terminal, then the big red wire from the starter solenoid. Wrap the wire terminal tom prevent shorting, reconnect the battery terminal and try again. If nothing happens this time, replace the starter/solenoid. If short is still present with starter unhooked, trace wire back from starter to find short. Let me know if you have more questions.
I am looking at my owners manual for my 2003 Trailblazer Vortec 4.2L L6 (this is the inline 6, the option for a V6 is not available for the 6 cylinder). Per the owner's manual Spark Plug gap is .042 inches and the firing order is 1-5-3-6-2-4
If you have not worked on a 4L50E transmission before, leave it to someone who is familiar with the the 4L60E. The solenoid is in the valve body and i know some who have put things back together and needed to take it apart again over something simple as a servo pin in revers. Best thing to do is get the truck scanned at Auto Zone free of charge or at a transmission shop with a tech 2 scanner for DTC codes. If there is a bad throttle body sensor or it's misaligned, it would affect your transmission's performance. The throttle body sensor send's signals to the ECM which calculates the amount of transmission fluid pressure though out the shift points, if that signal is bad then your shift points and firmness will be affected. There is also a cheap and great performance upgrade for around $50.00. You have a Transmission shop swap out the servo's for a Corvette servo's, it can be done in 30 min with out taking the transmission down or removing the transmission oil pan off.
Recap, have the transmission fluid and oil changed and have the throttle body sensor tested. It should show a smoothgradual increase in resistance with out any fluctuation. You truck is 15 years old and it may have a dead spot on the sensor now and it may need to be replaced. Good luck and keep me posted, Be glad to help and you can also have the transmission shop do a transmission pressure line test.
So when you say 'it will not close' do you mean it won't stay latched or does it 'bang' as you attempt to close it and won't go into the opening all the way?
The reason i ask as it could simply be the 'claw' is stuck in the 'closed' position IF the door bangs and doesn't want to go all the way into the cab opening. IF that's the case then you can use a screwdriver and while holding the exterior button like you're trying to open the door and use the screwdriver to 'flip the claw' of the latch to the open position.
IF it closes into the opening but simply doesn't want to latch it MAY just need some lubrication. Spray it good with your favorite lube (WD40, etc) then work the 'claw' while activating the outside (or inside) button. If it still doesn't want to latch then chances are the spring inside of the latch mechanism is broken and the latch assembly will need to be replaced.
I know you have a '91, which SHOULD possibly be the same as the old '73-'87 regular pickup. IF it's the 'new' body style (1988-1998) then the videos aren't going to be of help at all.
These videos MAY help explain how things work and how the linkages clip onto the actual latch assembly;
Assuming you have checked all the relevant fuses and relays, check for a blown inline fusible link in one of the power wires from the battery to the ignition switch. If you need a wiring diagram, try Alldatadiy.com.
"...one light goes on another off." is the clue. The problem is either
* a break in the harness or harness connector; or
* a loose contact in the circuit board connector; or
* a crack in a trace on the circuit board; or
* poor grounding.
You may need a magnifying glass to find a circuit crack, and a small soldering iron to fix it.
First thing to do is check for fault codes, all you need is a paperclip to do this. link to instructions is below, also make sure you have correct fuel pressure. FAQ How to read older GM codes for free
Ok first question. Did you install an AC Delco fuel pump? If not, change the pump. Other pumps do not maintain the pressure that is required by the system. You say you have installed a new disturber, insure you are time installed correctly. Rough running usually is a vacuum leak, usually you can find it by spraying cab. cleaner around the intake manifold and components. Hope it helps
If the belt and fluid levels are correct there is a good chance it may be a bigger problem. The power steering pump may be the fault. At lower speeds a worn pump isn't turning fast enough to push enough fluid. When you REV the engine your speeding up the pump pushing more fluid. Get the pump checked. If that's ok your possibly looking at a problem with the rack itself. ($$$ Ouch!).
Did you bench bleed the MC before installing it? If not, that's the problem. MUST be bench bled or you'll always have air. If brakes lights are on, the brake switch is out of adjustment OR (since you replaced the MC), the push rod is out of adjustment