Hey all,

I've done a lot of searching for this issue, and aside from a thread or two that seemed unresolved, I have no idea where to go from here.

My Blazer, (01, 4WD 4 Door, 180k) has occasionally not been starting. By this I mean:

1) It normally runs with no issues/CEL
2) Randomly on attempting to start it later, I'll get all of the dash lights, accessories, etc. and the starter relay in the hood box clicks (I've tried swapping it so that isn't the issue either), but no attempt to crank from the starter.
3) I initially had the neutral safety switch replaced, since it would tend to start after moving the gear selector around/rolling the car a bit in neutral, but that was obviously not the cause.

I took it back to the shop and it did finally start for them by chance after just attempting to crank it 20-30 times (on top of the hour I spent messing with it). They figured it could just be a failing starter, but didn't want to suggest an unnecessary replacement, nor the cost of tracing corroded/shorted wires if I could do any of those things on my own.

My question is, where to begin looking from here? I could replace the starter on my own, but that would be an undertaking as I'm away from home at university, and would need to rent the tools to do it. I could look into wiring faults, but I'm not sure where to begin since it seems that everything at least until the hood box relay is working correctly. Anyone's thoughts would be much appreciated!

 

I would start with the easy and free task of checking all your main power and ground wires.

First check where they mount to the battery and make sure they are tight and clean(you'll need a 8mm wrench or shallow socket).

From there check under the battery tray- remove the wires from the battery with the 8mm, remove the battery hold down clamp(10mm on rear side of battery, you'll need an extension) and remove the battery tray(2 15mm bolts that go into the radiator support)

Check the power wires on both sides of the 175 amp mega fuse (on rad. Support)to make sure they are tight and not corroded.

Follow your power wire to your starter and check that connection as well.

Power wire to alternator as well for good measure(I don't think this would cause your issue, but might as well check them all)

Now follow your main ground wires

-from battery to passenger side framerail
-from battery to front passenger side of engine block
-from battery to body @ radiator support
- engine to body ground strap- back of passenger side cylinder head to firewall.

Start by checking and cleaning these. They're your cheapest(free) and easiest fix.

 

The best outcome is to catch the fault condition while its happening. Its a PITA when its intermittent but you will catch it eventually. Your start circuit is as follows:

Starter power:

Large black cable from battery directly to starter solenoid at starter.

Power that operates the solenoid and allows main power to starter:

Red cable from battery to 175A battery fuse
Red wire from fuse to 40A ignition fuse
Starter relay contact
Purple wire from other start relay contact to starter solenoid coil

Control path to energize starter relay:

Hot at all times
20A ignition fuse
orange wire
connector
red wire
ignition switch
yellow wire
crank fuse
purple wire
clutch or neutral switch
purple/white wire
start relay coil
coil to ground

So you either have improper battery power or ground at the starter, improper start power/ground to the starter solenoid or improper start signal/ground to the starter relay coil. I would start at the load and work back towards the battery. Either be ready with a meter at every start with someone in the drivers seat or attach a lead to each point so you have an active volt meter that you can see from the drivers seat at each start.

First see what happens to the main 12V power at the starter during a start attempt. Does it begin at 12.X volts and stay there or does it drop.

Next check the 12V energizing signal on purple wire going into the start solenoid from the start relay contacts to see if the system is attempting to engage the starter. What is the voltage?

Third see if the start relay gets the energizing signal from the ignition switch start circuit on the purple/white wire to attempt to engage the start relay and pass power to the starter solenoid. What is the voltage?

After these results we narrow down which of the 3 legs and go from there.

George

 

Thank you both for your input! I checked the wiring as you both suggested the best I could, and found no issues! So, I just bit the bullet and replaced the starter. Aside from the cramped space and a few bumps to the forehead, it was a straightforward switch. By chance I did find a use for those Harbor Freight wobbly socket extensions, they gave me just enough play to fish in my socket to get to the electrical connections. So far, it starts every time.

 

Glad you got it fixed.

George

 

ja, thanks for the feedback. Congrats on a happy ending. The starter replacement is one of those situations where 4WD gets in the way.