I have replaced the corroded and burnt front signal socket as I was told that could be part of the problem. Now another person tells me that if I do not have the oem flasher unit this might be the culprit.?????? Rather then listening to people telling you it's this or that , if you can't view a wiring diagram an use a DVOM - digital volt ohm meter an test the circuits an find the problem , your best bet mite be to take your vehicle to a qualified repair shop. There are a lot of training videos on youtube for leaning how to trouble shoot these type problems . This is how professional technicians learned ! Electric Testing Techniques You Need to Know Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia
If the fuse blowes you have a direct short to ground on the B+ voltage supply circuit for the right turn signals .
Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on lighting , then under subsystem click on exterior lighting . Click the search button then the last blue link..
When does the fuse blow ? As soon as you turn right signal on ? As soon as you install a new fuse ? How to test for short to ground ohmmeter vs test light Don't rely on others , learn to test ,not guess .
Well stop looking on forums , most of those people don't have a clue ! Looking at a wiring diagram of the starting electrical circuit for your vehicle ,then testing for B+ voltage an good grounds where they should be is how to find and fix the problem , not guessing an listing to other people on forums . Something that fixes there problem was just lucky guess. By you saying it won't crank i take that to mean that when you turn the key to the start position nothing happens ? Is this correct ? A lot of people get that mixed up with the vehicle won't start a run . Do you know what a wiring diagram is ? What a DVOM -digital volt ohmmeter is ? How to use them for testing a electrical circuit .
What size engine does it have ? Is it a 4X4 ? Manual or automatic transmission ?
Free wiring diagrams here http://www.bbbind.com/free_tsb.html
Enter your vehicle info. year , make , model and engine size. Under system click on engine ,then under subsystem click starting Click the search button then the blue link. Look at the wiring diagram , a lot of thing's involved . Ignition switch ,park neutral safety switch if it has a automatic transmission , clutch pedal position switch for manual trans , plus the starter motor relay ,starter motor . This is how professional automotive tech's find and fix electrical problems , it takes year's of training to get good . Plus thing's change all the time . Electric Testing Techniques You Need to Know
What with that many miles on it I would check the catalytic converter and muffler to be sure they are not plugged. If one of them get plugged it puts back pressure on the engine and won't allow the fuel to enter the cyl. to start the truck. Have you check the fuel pump pressure and the fuel filter.
If you want a quick check of the blend door system,clamp off the heater hoses,as you would if you were changing a heater core and drive as you would.Do not disconnect them,just clamp them.
Also,don't over look air flow through the a/c condenser at the front,any restriction of air flow or a slow fan or only one running of 2 when 2 are needed?
If it were low fuel pressure misfire , it wouldn't be cylinder specific misfire #2 , 4 it would be P0300 random misfire . I would think fuel injector's too . When hot they could be breaking down electrically , more resistance . If they tested electrically with a lab scope they would know for sure . Misfire from sticking fuel injector no fuel misfire
there is a module for the daytime running lights... usually located on the passenger side firewall inside the engine compartment.... it likely needs to be replaced. if you cannot locate it let me know i'll find more detailed instructions for you