Help! New Alternator Battery Light on when Cold

[Badbob]

Folks--thanks in advance for your expert advice.

I got a 98 with 295k. I just replace my battery with a DEKA 800 cca and this high output alternator from ACE

1998 Toyota 4Runner 3 4L 6CYLINDER 130AMPS Alternator 1 Year Warranty | eBay

Everything installed fine. Belt is tight. Battery connections tight. Cleaned the ground to the fender well, etc.

However, now when I start it in the morning the battery light is on. But after the engine warms and I SHUT IT OFF and restart the battery light goes off.

I've been documenting the battery voltage for several days:

Upon install:

Engine off=12.32
Idle=14.54
Load, 2k rpm=14.51v

Day 1

Engine off=12.55
Idle=14.31
Load, 2k rpm=14.27v

Day 2

Engine off=12.22
Idle=11.6 [14.62 after restart]
Load, 2k rmp=14.54
Turned off 12.55

It is obvious that the new alternator is not charging upon startup, but after it warms and I restart the engine it charges.

Battery is solid and each morning the engine cranks and starts right up.

But the damn battery light is on.

Any ideas? Thanks!

 

[LittleCaesar]

If you still have your old alternator, put it back in if it was working and see if things change. I would think a.new battery standing alone should.be reading at least 12.5 if new

 

[greenbomer]

Call ACE and tell them what it's doing. Or take the alternator back.

 

[Badbob]

Call ACE and tell them what it's doing. Or take the alternator back.

Ya, I wrote them yesterday and they said they would work with me. He also wrote and said the V-regulator has a 5 sec delay. I check it out this morning and post. I'll check the connector to make sure I got 12v on each of the 3 wires with key in on. Perhaps I cracked something when installing.

Otherwise, out she comes and back to ACE.

thx Rob

 

[Badbob]

Ya, I wrote them yesterday and they said they would work with me. He also wrote and said the V-regulator has a 5 sec delay. I check it out this morning and post. I'll check the connector to make sure I got 12v on each of the 3 wires with key in on. Perhaps I cracked something when installing.

Otherwise, out she comes and back to ACE.

thx Rob

Checked it again.

12.8 volts cold
12.0 volts at idle
12.0 volts at 2k rpm

check the belt, no slippage
check the 3 pin connector 11.8v, 12.2v, 12.3v

Sigh . . . my suggestions "resetting the computer" not sure one could do that with this 4runner.

Any ideas?

 

[TheDurk]

Sounds to me like it may be the alternator is failing to self-excite rather than needing to warm up. Confirm this by revving up to 3k+ and seeing if the voltage ramps up as this is done and then stays up. If so, this is either a poor connection in one of the small wires (probably the S wire which is white in 2002--not sure about your year--or a defect in the alt. Make sure your 7.5A Alt S fuse is good. S stands for Sense, if you are wondering.

A dead indicator bulb will also do this but not your case.

For 2002, only one available to me while I am out of the US:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/014cs.pdf

 

[Badbob]

Sounds to me like it may be the alternator is failing to self-excite rather than needing to warm up. Confirm this by revving up to 3k+ and seeing if the voltage ramps up as this is done and then stays up. If so, this is either a poor connection in one of the small wires (probably the S wire which is white in 2002--not sure about your year--or a defect in the alt. Make sure your 7.5A Alt S fuse is good. S stands for Sense, if you are wondering.

A dead indicator bulb will also do this but not your case.

For 2002, only one available to me while I am out of the US:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/014cs.pdf

1998

Reviving when she is cold did not increase the volt output. Absolutely no change. The only thing that changes is when the engine warms and I shut the engine off and restart, then I get the full 14+ volts.

Ok, I'll check the fuses. I think I will pull the alternator out today and have a closer look at the connectors. I'll put the old one back in and see if the light goes off.

 

[Badbob]

ALT-S fuse is fine. 0 ohms, not break.

Funny thing--today I check the output at cold startup, again 12v, battery light is on.

After running for a minute the output went up to 14.6v and the light turned off on its own.

Strange. I cranked the belt tight. Will check it again tomorrow. If the light comes again then I'm pulling it out.

Rob

 

[TheDurk]

ALT-S fuse is fine. 0 ohms, not break.

Funny thing--today I check the output at cold startup, again 12v, battery light is on.

After running for a minute the output went up to 14.6v and the light turned off on its own.

Strange. I cranked the belt tight. Will check it again tomorrow. If the light comes again then I'm pulling it out.

Rob

Still, if it's a connection issue, it is most likely to be the Sense wire that goes from the alt. to that fuse. I would check that you have full battery voltage at the white wire on Terminal 3 of the alt. plug with ignition on and engine not running as well as at the red/blue wire to the GAUGE fuse on Terminal 2. The alt. needs those voltages to excite and that is what is not happening. The Light circuit on Terminal 1 appears to be working as it should. Otherwise, I have to figure it's the alt. itself.

 

[jasontrd]

I'm having a similar problem to yours. I put a new battery in a year ago and recently the battery light would come on and at night the lights will go bright and then dim and go bright intermittently. I replaced the alternator and no change. I will replace the ground cable completely to see if that helps but perhaps I'm having a connection issue in similar to yours. Once the weather warms up a bit here in WI I will pull and clean the cables and report back. I wonder if Deoxit spray would help with the connection? I happen to have some and will give that a shot this coming weekend. I will also pull some voltage readings as well.

-jasontrd