Blazer wont start!!
 

Well, just like the title, my Blazer wont start. I pulled the starter and had it checked and it's fine. I re-installed and cleaned all the terminals. When I turn the key I hear a "bonking" noise under the dash. It kind of sounds like hitting an empty pot with a wooden spoon, if that makes sense. The noise comes from the passenger side from a rectangular box under the glove box area. Could it be a bad ignition switch? Has anyone out there experienced the same thing. Any help would be appreciated. Thanks!

Re: Blazer wont start!!
 

Crickets................................ Lol.

Re: Blazer wont start!!
 

Ask on the general truck forums for a bigger audience.

Re: Blazer wont start!!
 

Is it turning over and the flywheel is not engaged? Did the issue just start happening out of nowhere?

I had a starter that wouldn't engage the flywheel unless I hit it with a hammer while a friend started it. Took it to autozone and it tested fine 5 times...but I still returned it for a new one...truck started up on the first turn.

Re: Blazer wont start!!
 

Thanks mtully79. No, the motor does not turn over at all, just the "bonking" noise under the dash.

Re: Blazer wont start!!
 

I don't know about the bonking sound under the dash, Its probably coming from the starter and resinating into the cab through the passenger footwell. Sounds like the drive gear on the starter is out of alignment and is butting up against the side of the flywheel or flexplate instead of meshing with the teeth on the flywheel or flexplate. You may have lost a shim. I would check that out.

You can determine if the problem is in the starter switch or solinoid by bridgeing the terminals on the starter with a screwdriver and seeing if it works. This is also a good way to see if the starter gear is meshing properly, or just butting up against the flywheel/flexplate. It the starter gear is not allowed to fully extend into the meshed position, I don't believe that it gets power to turn.

Re: Blazer wont start!!
 

Thanks for the answers guys. I know this is going to sound funny, but it's been too cold and rainy to get any work done on the Blazer. Waiting on some nice weather to check it out.

Re: Blazer wont start!!
 

x2 on the bridging the terminals.

If that fails, check the wires going to the starter. There should be at least one 12 gauge Purple wire. This should have 12 V when cranking.

If there is another wire, I think it should be yellow, it should be hot when the ignition is hot (according to the wiring diagram).

Also, your starter may need to be shimmed.

Re: Blazer wont start!!
 

If your voltage is a bit on the low side the starter solinoid will try to engage but not have enough total power to and will make the exact noise you are mentioning, would try the jumper lead 1st between the stater terminals, make sure if it is a manual trans it is in neutral, just saying.

Re: Blazer wont start!!
 

I agree with the other posters that it's most likely your starter solenoid. BUT...

If you're sure the noise is coming from that rectangular box you're describing, it sounds like the heater relay. Does the wiring look like it's been hacked by a previous owner?

Unplug the heater relay, and see if the noise goes away when you try to start your Blazer. Let us know the result.