sudden no voltage on acc/ignition/start

[ricktb]

[Short Version]
turn key, no power. headlights come on, battery full. fuses good. need help.


[Long Version]
My car has been running great, and has worked for months and starts every time. About a couple weeks ago I go out to my car, and I turn the key nothing, absolutly nothing. No power windows, no turn signals, no wipers, no radio, no power what so ever.

My first thought was the battery was dead. Heres the weird part. I put the key in the ignition and it starts beeping (normal). Without turning the key at all, I can turn on the headlamps full brightness. I was able to move my seat back and forth, but that stopped just today. I tested the battery for voltage, perfect 12.8 V In fact I trickle charged the battery to be safe for 12 hours and tried again to no avail. I also tried boosting it off a known good vehicle which was running. No power.

My second thought was the ignition switch maybe wasn't connecting power through the switch to the ACC and ignition. I pulled apart the steering column and unplugged the harness leading to the switch. I tested the voltage there. 12.8V I manually bridged the main lead to the ACC, igniton and start. Each time the voltage dropped to 0V, the instant the connection was made.

I checked all fuses, only one 10 amp fuse was blown under the dash but I didnt see which one since I pulled them out together. I put in all good fuses and left the bad one to something like taillights for now. All fuses under the hood are good.

I also pulled the ECU and physically inspected it for signs of damaged compents or circuitry, and the thing looks great from top to bottom.

My last thought was maybe the main ground to the battery wasn't good enough it looks a little frayed, but it has looked like that since I bought thing 5 years ago. I have left it for now since the headlamps do come on no problem.


A little background.. a year and a half ago my car was stolen, and recovered two times. After I finally got it back the last time the ignition would not start. I received 0 volts to the main ignition harness lead. After weeks of troubleshooting I was unable to resolve the ignition issue so I ended up running my own power wire.

The circuit is like this.. battery positive -> 30 amp fuse -> switch (under dash) -> ignition. I have inspected this circuit and it gives a full 12.8 V until I switch the key to ACC/ignition/or start. This has worked great for the year and a half.

Also during the time between when I drove it ok last, and the time I encoutered the problem, I had the car on camera so it has not been tampered with.

Any Ideas?? Could there be a short which causes the voltage to drop to 0 without tripping any fuses? WTF?

I've added a short version who those who don't like reading. heh

 

[sniver]

Whats the state of the battery, could you have it load tested somewhere? The ignition circuit is not that hard, do you have a copy of the factory service manual so you can view schematics?

Also high resistance, or corrosion can cause issues like that. Think about pinching your garden hose, you get an initial burs,t then it tapers down to a trickle.

Another thought is a connector has poor terminal tension.

 

[2gGSX]

The same thing is happening to me after a wiring harness swap, and I'm also looking at doing an ignition switch because I can't figure it out!

Does your car have an anti-theft system? That's the last thing I haven't looked at in detail yet.

 

[Dsm4lyfe12]

This might sound stupid but did you try retightening the positive on your battery. If not loosen both of them and push them down as far as you can and retighten them.

 

[sniver]

This might sound stupid but did you try retightening the positive on your battery. If not loosen both of them and push them down as far as you can and retighten them.

This is good advise, I tend to overlook what I think is common sense.


Sent from my Droid

 

[Dsm4lyfe12]

My car would idle like crap/ i would try to start it and nothing. Push the terminal down and that was my problem. For some reason mine like to come loose ALL THE TIME.

 

[agarc023]

My car would idle like crap/ i would try to start it and nothing. Push the terminal down and that was my problem. For some reason mine like to come loose ALL THE TIME.

Do this and clean the terminals and the posts. Mine would turn on the lights and everything, but refused to turn on. Cleaned everything up and the car started up like a champ

 

[ricktb]

Heres an update: I reviewed my security camera footage and I noticed a wet spot on the roof directly over the dome light for about 72 hours a couple days prior to this happening. The rest of the roof was covered in a light coat of white frost. Between that time and when the issue happened I maybe drove my car 3 times, for 15 minutes to a half an hour each time. Weird since I had no trouble starting the car, if the battery was dead.

Suspect a dead battery from the dome light. (optima yellow-top)

I will have my battery load-tested as suggested by Sniver, and re-charged/re-placed if needed. I will also create a brand new ground wire to replace the old freyed one, and clean the battery terminals as suggested by agarc023.

I also read optima batteries require special recharge methods, has anyone had to recover a deep cycle battery before, and could lend some tips? I don't know much about these bat's . I have a motomaster 2/15/100 amp charger with a deep cycle switch on it..

I will update again after, with the results. Thanks for the insight.

 

[ricktb]

UPDATE>

Success! Problem Resolved.

I had the battery load tested. It came back ok and fully charged.

I changed the old ground cable, battery post clamps, and sanded all the visible corrosion of the connectors, trimmed back the wires to fresh copper, and the car started right up!

Thanks for the helpful advice I may not have thought it was the battery connections, and might still be ripping apart the harness or something. Going for a joy ride..

Here is a pic of the fresh connections