Electrical Issues

Asked by Jul 17, 2016 at 01:00 AM about the 1999 Chevrolet Blazer LS 4-Door 4WD

Question type: Maintenance & Repair

Truck would turn over but not start and was found with bad fuel pump.
Replaced it and assembly. Day later it shut off while moving in drive 2
times. A second mechanic found no obvious causes and said it threw no
codes on a Tech 2 knock off scanner. When it shut off once for him he
tested and found NO fuel pressure. He checked pump wiring, battery,
alternator and found nothing. It has not shut off since back from second
mechanic BUT the horn works off and on and now the display lighting for
the gear selection (PRND) is going off and on. Seems like a systemic
electrical issue. Any thoughts?

6 Answers


Your truck could be stuck in 2nd gear therefore when you stop your motor doesn't have enough power to stay on due to the stress from the trans. My truck done the same thing. It could be a few things but if p r n d is messing up it could be the ignition switch. But for my truck it's was the wires going into the trans. The plug was dirty and it had fluid in it due to a leak. Try looking at that plug and cleaning it out. Take off your battery also to reset the computer

1 people found this helpful.

If your ignition switch is messed up your truck will go into limp mode not trying to say your Trans is messed up by staying in 2nd it's just a safety feature.

1 people found this helpful.

Thank you I appreciate your insight. The times it cuts off it is running and has been for several minutes. It was usually idling forward slowly and simply shut down engine and electrical except a battery light in the dash display. Also would the ignition switch or wiring cause the horn to go in and out or the fuel pump to test at zero fuel pressure when at the mechanics? What do you think about it being a fuse/ relay? Does anyone know if there is one that connects horn, dash, fuel pump??


I really don't know about the horn but if the wires are corroded or the pins in the mechanism of the ignition switch are corroded it wouldn't give voltage to the fuel pump or dash. If you have ever had to hot wire a vehicle you have to have 4 wires touching for your vehicle to run and shift gears one gives power to the dash lights and fuel pump. Because you have two turns to make for you fuel pump to turn on the first position gives power on the inside like radio and horn. The second and last you will hear your fuel pump turn on. I would just do a lot of research especially about an ignition switch going bad and symptoms.

1 people found this helpful.
Best Answer Mark helpful

Thanks hotrod I appreciate all the help! The car is miraculously running fine, and no dash light issues but now the horn is completely dead now. I will check the wiring though, it sounds like that's the issue for all three!


No problem. Electrical issues can be the worst

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