No power (no lights on dash when turn key), No crank 1992 gmc sierra 5.0L

[Vddiaz94]

Good evening, Everyone i wanted to ask anyone familiar with troubleshooting electrical problems on these GMT400 trucks. I currently have no power no lights on the dash no fuel pump activating etc. I first wanted to rule out the ignition timing aspect is it possible to have zero power if the firing order is off? regarding distributor wires to spark plugs. For example, would having a mismatch of these distributor wires cause my truck to just not start? Im going to a AutoZone tomorrow to see if my Optima battery is okay it was before i started wrenching on my oil pressure switch due to a leak. Could it be that i shorted something out? I'm in a dilemma I'm not sure if i did completely short something out due to incorrect firing order I'm saying this because when I plugged everything back in after the job I did have lights on the dash but no crank. I have a feeling I left something unplugged i did see a purple harness that was unplugged but I thought it was something the previous owner did intentionally. The purple wire is near the distributor close to the firewall.

Thanks,
Victor Diaz

 

[scott2093]

would having a mismatch of these distributor wires cause my truck to just not start?

Sure... but not no lights, no fuel pump prime,etc...
Have you super checked your battery cables? Can you read the voltage on your battery? Maybe try to get a reading from alternator stud to a ground...or even check for continuity from battery negative to a ground...to make sure you at least aren't missing something.. Could see if you blew a fusible link either at battery positive or at the junction block....
I think the purple wire may be for an additional o2 sensor that some of these trucks don't have but I'm not totally sure....

 

[Vddiaz94]

I was planning on checking the battery and buying a multimeter. I'm a new buck in this field. I did semi check the battery and it seemed okay nothing out of the ordinary. That's what I was thinking as well i changed the 02 censor a while back so it seemed familiar. Thank you Scott for your response.

 

[scott2093]

That's what I was thinking as well i changed the 02 censor a while back so it seemed familiar.

You'll figure it out. I'm sure it's something simple. And if you were able to win the fight of changing your O2 sensor, you're going to be just fine....lol
be careful with that oil pressure switch.. Very delicate area.. Take your time for sure...

 

[Vddiaz94]

Yeah, that's what I keep telling myself bro lmao. I've got basic experience with GM motors but more with trans. I haven't gotten around to the power side of things most I've done was replace a pigtail to my knock sensor. These forums and online info make troubleshooting a lot more manageable. Thanks again Scott will do man.

 

[Vddiaz94]

Update: Everything turned out well! I did a second inspection like you said and noticed loose terminals that were held by electrical tape. I cleaned it and fastened it and re wrapped it well and lights on the dash! my battery also was discharged and checked the junction box and made sure the fuses were okay. I think ill hold the oil pressure sensor off for another day or weekend I'm just happy my truck is okay.

 

[Vddiaz94]

Thanks again, Scott.