Hi all, I apologize in advance if another thread covers this, I've already found several threads on here and tried the solutions presented but to no avail. I may leave some info out so please ask away, I will try to tell you everything I can to help.

I bought this 2001 Blazer (Trailblazer trim) in November and it has been down 6 times now. I've fixed everything as it comes up but can not diagnose this one. Water pump, crank sensor, starter, radiator, cap/rotor, wires, plugs are all new. It ran perfectly fine for about two weeks then one morning it wouldn't crank at all. So far I have tried a few different batteries, verified that the starter is receiving power, installed a resistor to bypass the PASSLOCK system, opened up the floor shifter and inspected/cleaned all the wires/plugs in there. I've inspected every fuse I read about on here. The security light does not illuminate, the fuel pump does not cycle when I key it forward. The shifter is stuck in park unless I manually slide the white circle piece I learned about on here. When I click the button on the shifter, the PASSLOCK makes an audible clunk that I don't remember. That is all the info I can come up with off the top of my head

Please tell me what you think I should try next or if there is any information you need from me to help me out. Thank you!

 

1. What is the resting battery voltage?
2. Same question with the ignition in the start position?
3. Pull the crank fuse and tell me the voltage at each fuse socket with the ignition in the crank position.

Meter black lead on battery ground for all measurements


George

 

[QUOTE=GeorgeLG;752621]

1. What is the resting battery voltage? 12.07
2. Same question with the ignition in the start position? 11.97
3. Pull the crank fuse and tell me the voltage at each fuse socket with the ignition in the crank position. The socket nearest the front of the vehicle reads 0v the other reads 11.95

Meter black lead on battery ground for all measurements

sorry for the delay, had a caliper seize up on my other vehicle yesterday coming home from work

 

No problem we’re on your schedule. I’m always here.
you need to get that battery charged up, a fully charged battery is 12.6 V at rest and you’re not charged up enough to reliably start the truck. That said you’ve got other problems though, so let’s keep tracing down your main issue. You’ve got voltage from the battery through the ignition switch to your crank fuse, so let’s find out where the problem is. It’s somewhere between the crank fuse in the starter, which involves the relay the neutral safety switch in the wiring. Crawl under the truck get a solid frame ground with the meter black lead, then touched the always hot large black power wire on the starter with the positive lead of the meter to make sure you’re getting a good reading then move the positive lead over to the small terminal with a purple wire on it on the starter solenoid and tell me, what voltage you get when somebody turns the ignition to the Start position?

George

 

Is there a way to reply without quoting you? Or do I just delete your message and type mine every time?

I just checked that out, I was getting a reading of 11.96 from the always hot wire but I wasn’t able to get any kind of reading from the purple wire when the key was in the start position. I don’t remember if I mentioned this yet but I tried starting the blazer with a screwdriver and the starter worked flawlessly then. I still wasn’t able to start it though as the fuel pump isn’t priming when I key forward.

 

Just hit reply to thread if you don’t want to quote me. OK so your starter problem is somewhere between the crank fuse and the purple wire on the starter solenoid. Is this an automatic or manual transmission?

George

 

This is an automatic

 

OK, so then this is either the start relay or the park neutral switch on the side of the transmission or the associated wiring. We’re getting close. It’s dealers choice on whether we check the transmission switch or the relay first but since you don’t have to crawl under the truck for the relay. Let’s start there. Black lead on the meter to battery ground post, pull the relay, take a positive meter lead and probe all four sockets. One of those sockets should be. Always on 12 V and with the ignition off there should be no voltage on the other three sockets. Then turn the ignition switch to the Start position and see if one of those three dead sockets gets energized with 12 V.

George

 

Any tricks of the trade for getting a reading on the relay sockets? The klein multimeter I have doesn’t reach far enough into the socket to pick anything up

 

A paper clip or thin piece of metal, just don’t spread the sockets open by forcing something thick in there. Try to copy the thickness of the relay pins.

George