No power unless talon is running!

[zroth05talon]

The symptoms are pretty simple, well actually nothings simple when it comes to dsms, no power to any systems in the car (door locks, windows, radio, fans...) besides the dash lights and ignition when the car is off. Even with key in the on position. When the car is running on the other hand everything turns on, but there is a very noticeable power drop when anything is turned on, as I can tell by the headlights almost turning off, then returning to normal after the alternator picks up the slack

 

[Jiggalude]

Sounds like you have either a bad alternator or a short somewhere draining you power.

 

[steve]

Check the alternator fuse and the white wires from the battery to the alternator fuse.

You may have to pull it to actually measure the resistance with it out of circuit.

 

[thomcasey]

Why would it be the alternator??? Since there is NO POWER when it isn't running, then has the battery been checked? Maybe it will not hold a charge or has bad connections/ground. Since the car runs once jumped, then the alternator is doing it's job.

Take the battery to Autozone or something and have them test it for free, in fact, have them test the alternator too. If they both pass, then look at connections.

 

[Jiggalude]

Why would it be the alternator??? Since there is NO POWER when it isn't running, then has the battery been checked? Maybe it will not hold a charge or has bad connections/ground. Since the car runs once jumped, then the alternator is doing it's job.

Take the battery to Autozone or something and have them test it for free, in fact, have them test the alternator too. If they both pass, then look at connections.

This is true BUT he's getting lights on the dash and no where else. If it were the battery why would just the dash light up but no other lights? Are the fuses for the interior lights different than those for the dash lights?

 

[zroth05talon]

Had both tested and checked out ok. The alt and batt are brand new. It seems like whatever hot wire is suppose to on isnt until the car is on. I checked all the fuses and they have energy. Could it possibly be the ECU?

 

[Jiggalude]

did you check the fuses for the interior lights?

 

[zroth05talon]

Yeah checked all the fuses and all have energy.

 

[Jiggalude]

What happened right before this issue started?

 

[zroth05talon]

Arc between old alt and exhaust.

 

[Jiggalude]

And all fuses and relays have been checked? I would assume some type of short if you've checked every single fuse in the engine bay and under the dash. Either that or all the bulbs were blown for some reason

 

[steve]

How clean are all the connections to the positive terminal of the battery?

Take a look at the power distribution diagrams in the electrical section of the Factory Service Manual and start measuring the voltage on the sections that aren't working. As you get closer to the battery you'll find the point where you don't have power and then do.

 

[92_foxgt]

check for corroded grounds and power wires. Might be just enough flow in the wire to support low amps like dash lights, and then when the alt fires up it produces enough amperage to push through the high resistance. If you had a corroded batt cable and just replaced the end then the cable probably need sto be replaced. The corrosion will creep all the way through the cable. I had a blazer I worked on that had power to everything, worked fine, voltage checked good everywhere. Tried to crank it, and it would just lose power to everything for a minute or two. Someone had spliced in on the original batt cable and the corrosion had ruined the cable

 

[EuroDriver]

I would focus on the short and not what has power.

Finding the short...

This is what I would do...

Disconnect the battery and conduct a OHM test to check for a ground at the battery terminals... it SHOULD be OL. (no connectivity)

>You should have a draw.. so, it would give you a resistance value << (BAD)

NOW, disconnect ALL the fuses and recheck the connectivity.

(you are removing possible broken wires by doing this and narrowing down the problem down to a specific harness) How crappy would it be if the radio was the problem?

1) IF you have no connectivity, then you somewhat found the problem.
*Start replacing VITAL fuses first (head lights, turn, ect.), re-checking the OHMS as you go.
*You will find the problem in no time

2) IF you have connectivty, then you have somewhat found the problem. (this means that your MAIN harness has a problem)
*From here, it gets sticky... and I cannot describe what I would do. Just use good judgement.

Good luck!

 

[steve]

This is what I would do...

Disconnect the battery and conduct a OHM test to check for a ground at the battery terminals... it SHOULD be OL. (no connectivity)

There are things in the car that are always powered like the ECU and radio. So measuring across the positive and ground with the battery disconnected will show some non-infinite resistance.

 

[EuroDriver]

There are things in the car that are always powered like the ECU and radio. So measuring across the positive and ground with the battery connected will show some non-infinite resistance.

Thanx for the heads up...