Few weeks ago my 1999 s10 Chevy Trailblazer V6 4.3L died when I turned it off and found it unwilling to restart. I had crank and I had spark, so i begain looking at fuel pump issues as I did not hear the pump come on.

I've verified all fuses and relays are in working order, but found that the 2 second fuel pump pulse wasn't activating after testing it from that pinhole in the fuse box. Swapped the computer with a spare from an identical vehicle- still no fuel pulse. EDIT: swapped the orginal computer back right afterwards

I'm still getting crank + spark at this point.

So I ordered a new Ignition switch to replace the old one. Upon removing The old one I discover the previous owner had gotten a remote start installed. When they installed it, they seemed to have added bypass connections to the orginal harness which ran to the remote start unit - but nonetheless left the original harness in its default wired state. So in my mind, it's just a parasitic add on that hasn't changed anything underneath.

So I removed the unit, having to cut three wires from the unit in the process. Everything else was just plug and play.

Now, having installed the new Ignition switch I have found that the vehicle won't crank (before it would). Obviously one of those wires did something. It's just confusing to me, as the ignition should now be returned to its orginal unmodified state now that I've replaced the modded switch and it's harness.

The security light is not on - to my knowledge, would the pass lock system not have already been bypassed by the orginal remote start install? Do I have to re-bypass it after installing the new Ignition switch?

Turning to the remote- start box I removed, I'm not sure if I can trust the color coding between where the connector I cut goes out and where the spliced wires from the switch harness come in. Making the pin-out guide a little useless as I'm not certain which wires from the switch these actually connect to.

So just going into the remote start box we have;

- A red wire that splices into red-white on main ( d2, Ignition switch output crank on/off)
- first purple that splices into orange on main ( c6 , ignition switch output 3)
- A second purple that splices into bright yellow on main (d1 , ignition switch output crank)
- A yellow that splices into pink on main (c5, ignition switch output 1)
- Asecond red splices into solid red on main (b1 , fuse output battery)

Now heres where the wires coming from the remote start (the cut ones) ran previously;

- purple ran to ignition coil,
- orange ran to white wire (a1? Stop lamp output) on main harness
- yellow ran to light blue wire in dash (cruise control?) This wire is still hanging down in pics.

Appreciate any relevant info / tips. I'm confused as to how replacing the unit renders any of the circuits any different than before - except for the yellow wire that is obviously unattached from anything.

Also not too sure what this box attached to the OBD line is - it's not related is it?
plus there is an empty plug space just below where the harness bolts in - but it was empty before I started, so again I assume its not related?

 

Its a shame that we did not have a chance to correct the fuel pressure issue before all of these changes were made.

1. The new engine computer has probably created a passlock problem. Can the original computer be put back in the truck?
2. Did you test for 2 seconds of voltage at the fuel pump priming tab in the fuse box or did you attempt to hot wire the fuel pump at the tab with 12V?
3. Did you replace the ignition switch before or after the removal of the remote start module? If before did that change anything?

George

 

1. Updated post, reinstalled it immediately after intial swap.

2. I tested for voltage at the pump, found nothing, then went and tested the prime tab in the fuse box - again nothing - verified power at fuel pump relay and I verified the relay works. I also verified the pump works by running 12v directly to it.

3. Those Two events coinsided with each other, however- since what I am replacing is just the switch/contactor box, I can re-install the remote start by just soldering the three wires I cut, and then splicing everything into the new switch to see if that works

Regardless of being unable to crank due to the ignition switch change, I know that the fuel pump relay isn't switching on and that the fuel pump prime is not occurring. I've also verified that the crank position sensor is reading.