How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Mike S. Your Own Question
Mike S.
Mike S., Chevy Mechanic
Category: Chevy
Satisfied Customers: 6925
Experience:  ASE Certified Master Technician
20625509
Type Your Chevy Question Here...
Mike S. is online now
A new question is answered every 9 seconds

I have a 3006 Impala 3.9 v6 LT and the car has no electrical

Customer Question

I have a 3006 Impala 3.9 v6 LT and the car has no electrical power to anything. Just like disconnecting the battery. Nothing electrical is working.
I heard a very faint clicking on one relay. I removed the relay and clicking stopped and put back in the clicking started again. When I disconnected the neg batt cable and reinstalled the clicking stopped.
The relay cover says PWR/TRN on that 4 prong relay. Can a bad starter kill all electrical power to the car? Even the headlights don't come on. The battery charge is good. Nothing electrical works just like a disconnected battery.
Submitted: 4 months ago.
Category: Chevy
Expert:  Mike S. replied 4 months ago.

do you have a voltmeter or at least a 12 volt test light?

if so, do you have voltage present at fuse #BATT 1 in the underhood fuse block, mounter to the right front strut tower?

Expert:  Mike S. replied 4 months ago.

To answer your question about the starter, no a bad starter would not cause you to loose all electrical. Here is the power distribution wiring diagram, if you don't have a voltmeter or at least a 12 volt test light, I see that the radio is almost a straight shot from the battery, so does the radio work or at least come on?

Expert:  Mike S. replied 4 months ago.

While you are at it, check those BATT fuses in that underhood fuse block, cause they feed the I/P fuse block.

Customer: replied 4 months ago.
Ba#1 only shows 1 volt. Batt #2 shows 11 v
Expert:  Mike S. replied 4 months ago.

1 volt is no good, 11 is ok.

Is that 1 volt on both sides of that batt1 fuse or just one side of the fuse?

Expert:  Mike S. replied 4 months ago.

I am assuming though the battery is only at 11 volts, is that correct? If not, batt 2 fuse should be whatever the battery reads, no less than 0.2 volts less.

Customer: replied 4 months ago.
I connect one lead from v meter to top terminal and other lead to bottom terminal. got one v
Expert:  Mike S. replied 4 months ago.

No, that isn't the way you should hook up the voltmeter. hook the negative lead of the voltmeter either to a clean metal ground or the negative battery pot if it will reach that far, then touch the positive voltmeter test lead first to one side of the fuse and then to the other side of the fuse and make sure both sides of the fuse have battery voltage (12 volts) all the time, for those BATT fuses that is.

Customer: replied 4 months ago.
battery is 12.34 v and the batt#2 fuse shows 11.4 to 11.5 v #1 fuse show about 1v
Expert:  Mike S. replied 4 months ago.

1 volt on both sides of the fuse? Did you ground the voltmeter like I said?

Customer: replied 4 months ago.
ok doing it that way I have 11.5 v o bottom terminal and.5v top terminal on batt 1. batt 2has same reading on bottom term but top terminal is 0 v
Expert:  Mike S. replied 4 months ago.

I think you have a bad fuse box. If you remove it you may see the problem, probably some rust maybe or it burnt through underneath.

Expert:  Mike S. replied 4 months ago.

replace both of those fuses and check them readings again.

Expert:  Mike S. replied 4 months ago.

maybe it's not the fuse box then.

Customer: replied 4 months ago.
need go into town and get the fuses.
I didn't ask if the starter was bad could that be the problem. I asked if the starter relay was bad could that cause a total power loss. My Silverado when the starter relay is disabled then I can't use the key fob to unlock the door even.
Customer: replied 4 months ago.
Also what is the PWR.TRN 4 prong relay for? It was clicking when nothing else was working. When I disconnected the battery the clicking stopped and didn't click again when I reconnected the battery.
Expert:  Mike S. replied 4 months ago.

no that is not what you asked, you asked, "Can a bad starter kill all electrical power to the car?" Either way no, the starter relay could not cause all of the power to go out, unless maybe it blew a main fuse.

What do you mean by, "when the starter relay is disabled"? How are you disabling it? If removing the fuse, then if that fuse also feeds something else, it too won't work then.

Expert:  Mike S. replied 4 months ago.

It's the relay that powers the engine control module among other things. it's on that fig 4 of the wiring diagram.

Customer: replied 4 months ago.
I have a theft deterrent starter relay on the Silverado which disconnects when ignition is shut off. I reset the relay by remote fob.
Customer: replied 4 months ago.
Have to go get fuses. Will see what happens then but I think fuses will not fix the problem.
Expert:  Mike S. replied 4 months ago.

They should unless you were hooking up the voltmeter wrong.

from the readings you gave me, both of them fuses were blown.

You said, "I have 11.5 v o bottom terminal and.5v top terminal on batt 1. batt 2has same reading on bottom term but top terminal is 0 v' First of all, I assumed you meant .5 volts when you said, "batt 2has same reading on bottom term". anyhow all readings should be 12 volts.

Customer: replied 4 months ago.
I replaced the starter relay and the PWR/TRN relay plus both batt fuses. The car is functioning ok now. I know the top fuse had checked ok but I replaced both anyway. I was just guessing that perhaps the starter relay or that clicking PWR relay could have been the problem so I replaced both. So throwing parts at it fixed it.