No Spark

[ShutGate]

Greetings

 

I have a 1999 1500 series 2WD 5.7 Vortec, it will crank but will not start, checked all fuses and relays, replace crank position sensor, ignition module, camshaft position sensor/pickup coil and fuel pump to no avail, still cranks over but will not start

 

the truck ran fine, was parked and then would not start, the fuel pump would not come on, replaced relay and pump, still nothing, spoke to a friend and they say if it has no spark it will not fire the fuel pump, so we checked for spark and it has none

 

thats when we started replacing sensors etc., upon further checking we found it has no fire going to the coil(coil was tested at an autoparts store 3 times checks good) no fire getting to the distributor or the crank position sensor, the fuse box gets fire and when the ignition is on/spinning over everything seems fine, fuseable link coming from the battery is also good, checked the ECU and it looks fine, no obvious signs of damage.. but its rather expensive to replace on a "might be bad"

 

what else can we check, seems the fuse box has power.. but nothing gets that power, broken wire maybe? been checking but found nothing

 

the truck had a strange key/switch type alarm or disabling device under the dash, unplug it and the key does nothing, its just a simple switch wired between a yellow wire that goes to the ignition.. it seems to function, but i just thought i would throw that out there

 

the fuel pump works if you take the cover off a relay and "force" it, but the truck still gets no fire to anything and will not start

[blacksierra01]

If theres evidence of any aftermarket auto start/anti-theft devices, that is where i'd start looking, I've seen quite a few go bad from poor instalations

[ShutGate]

If theres evidence of any aftermarket auto start/anti-theft devices, that is where i'd start looking, I've seen quite a few go bad from poor instalations

 

Indeed, that was one of the first things we checked, as far as we can tell it is simply a "switch" with a special key that turns it on or off, we have no key for it, unplug the switch and the ignition key does nothing when you turn it, the aftermarket switch was wired between a yellow wire that leads to the ignition switch, it also had another plug that had a ground and a small red wire, with a small plug that was plugged into a red wire near the yellow wire, we eliminated the aftermarket switch by wiring the yellow wire back together, not sure what the smaller plug to the red wire was for, there was no change with it plugged in or unplugged

 

 

we replaced the ECU with another used ECU from a running truck (same ID number on the unit) still no change, no signal going to the coil or crank sensor tach does no move when you crank the engine over

 

its been suggested that the timing could be off, not sure how it could jump time, but a friend says the engine will not fire if the timing is off to protect it, how true is this? replaced nearly everything that can be replaced within reason, at this point i am stumped, my last guess is either the aftermarket "security system/anti-theft" switch is the cause, maybe somehow we missed something? but the engine ran with previously.. or possibly the timing has jumped? maybe something catastrophic has happened so the engine refuses to send a signal to fire?

[ShutGate]

ok, officially &^*%!# off at this $%@#% truck

 

all this time and money to fix it, and it was a missing fuse, the diagram for the fuse/relays under the hood is mostly non legible, so we could not see what was what exactly, found picture online and noticed a fuse was missing, the "ecm-i" or something to that effect, was gone

 

stuck another spare fuse in and boom, fires right up and runs fine, i hate working on vehicles that someone else has tried to "fix" beforehand, not sure if it was one of the replacement parts and the fuse.. or just the missing fuse all along, not going to bother backtracking to find out either

 

 

thanks for your time and bandwidth i suppose