2003 Tundra with 295000 miles but then......

Hey all. Loved the Tundra and bragged about it for years. I sold it to a employee and two days later all hell broke loose. Mechanically it is still great but....electrically died. Will not start although it turns over unless the battery has been over charged. Remove the battery cable and it stalls , checked the alternator twice and it’s good, battery is good and has been replaced. I did have a problem with a relay or two at one time. It will not stay running. All thoughts are appreciated!

 

/thread. Apparently you already solved your problem...

 

How’s the alternator?

 

The alternator checked out perfectly when I removed it from the truck. If I disconnect the battery cable from the battery with the truck running the truck does stall. Unless the battery is overcharged then it will run for a while.. It's been baffling.

 

How do you "overcharge" the battery?

And how is the state of charge of the battery a factor if you've elimnated it from the circuit by removing the positive terminal?

With the truck running, and the battery connected, what is the voltage across the battery terminals? Should be 14+ volts.

 

Thank you guys for responding. When a voltmeter is placed across the two terminals it registers over 14 volts. That is what I meant when said overcharging it's over 12. The voltage drops when the cable is removed to 7 or 8 volts and then the truck stalls after a short. Of time. Like I said, before I had problems with the relays. Occasionally wiper fuse blew. But not much else happened other than that. The truck ran perfectly with 291000 miles on it. The engine transmission are perfect. Thank you for all of your suggestions.

 

Twelve volts is a nominal rating for a six cell automotive battery. Physics demands that a fully charged 12 volt automotive battery have 12.6+ volts. After all, who wants to say their truck has a "12.6V" battery? A smart charger will charge and maintain a fully-charged battery at 13.6V.

(1) Clean the battery terminals and inside cable ends of corrosion with fine sandpaper or scotchbrite. In severe cases, use baking soda solution first to neutralize any acid around battery terminals. If battery has removable cell covers, be careful to keep baking soda solution out of battery cells.

(2) Reinstall cables, and fully charge the battery to at least 12.6V, preferably 13V+. If battery barely reaches 12.6V, then your battery probably has sulphate deposits on the plates and is weak/dying.

(3) If steps above don't fix the problem, disconnect the cables or remove the battery from the truck.

(4) Charge the battery fully. Measure voltage, then let the battery set at least overnight and measure voltage again. If the battery loses voltage overnight while disconnected, you battery likely has a weak or dead cell.

(5) Replace the battery with a new battery that is fully charged.

(6) If the alternator does not keep the new battery charged, have the charging system checked out.

 

What about a bad ignition switch???

 

Thank you. Yes the electrical part of the switch has been replaced. This is driving me crazy! Open to all suggestions. Thanks.

 

From what I hear running your engine with the battery disconnected is a big No No with the computer in todays cars. Good luck with your fix.

 

I think we are all very confused on what is going on here..

Perhaps some better details could help us solve your issues.

You say it won't start?

But it's running when you disconnect the battery?

How is a battery overcharging?
Are you referring to when the truck is running reading 14v from the alternator?

What is the battery voltage when truck is off? How do you know the battery is good?

When it stalls is there any stuttering or rough idle first?

Is the check engine light on? Any codes?

If you keep your foot on the gas pedal a little when idleing does it stay running?

 

Yep, that is correct, according to Click and Clack:

https://www.cartalk.com/content/could-you-please-settle-argument-some-my-ham

 

TRD1stgen is right. Let's not get sidetracked discussing the exact volts the battery should have. OP, put down the coffee, tell us exactly what is happening in sequential order so we can help you with our amazing internet mechanic skills.

From all my years working on gasoline engines, the coils and spark plugs can only get electrons to perform their tasks from either the battery or the alternator.

You said the engine dies when removing the the battery cable so that clearly shows the alternator or alternator circuit is failing. Did a shop test your alternator for volts and amps?

 

2nd and 3rd to the suggestions and/or comments above from others.
My contribution would be to let your employee know he needs to take it to a qualified mechanic. I'll respectfully advise you to read the above comments, especially how to properly check a battery/alternator. Hopefully your employees veh is not damaged from you undoing battery while engine is running....zttttt !