Altenator/radiator lights on, battery dieing slowly. Help

[954TalonTsi]

First off this happened before but went away before I could check it out. On the way to work both lights came on and my TT read 13.8 before now its trickling down, at 12.1 as of this morning. Also my coolant gauge is reading cooler then anyother time, like thermostat stuck open... Ive checked ALL fuses, pulled altenator to test, read fine. Does anybody have a clue as what this could bebe???? Im stumped and ive spent last 2hrs searching post for similar problems. Please my DD is in need of your knowledge. Thank you in advance to this great community.

 

[GRAVEDIGGER]

Alternators can test out okay on some testers like autozone uses, so the only test I trust is the on car test. With the alternator on the car and the engine running you should be seeing somewhere between 13.5-14.7 volts at the battery on a good charging system. If you are not seeing at least 13.5 volts at the battery your alternator is most likely junk. There are some cases however where the alternator power wire going back to the battery is not up to par, so that might be something to check as well. Good luck

 

[laserspeeddemon]

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Check your belts.

 

[954TalonTsi]

Well my belts are fine, thats on the "basic" level of car care...
And as stated it tested fine at my uncles shop, still under warrenty so ill go get it replaced for shits n giggles. as far as the power cable that appears to be fine, no exposed wire or knicks. Can anyone else shed some light on my depressing situation??

 

[GRAVEDIGGER]

There's really nothing else to it. You either have enough charging voltage or you don't. The 12.1 volts you had this morning aren't enough.

 

[954TalonTsi]

I understand that much matt. Still, why would my my radiator light be on at same time? If I.replace altenator and its still showing same problems then wut?? Im trying to get to source of BOTH lights being on. My uncle is swapping the altenator out rite now so ill post update asap.

 

[GRAVEDIGGER]

It's not uncommon to have some dash lights on as the ecu gets silly and can sometimes throw random lights when the system is low on voltage. If you're sure the radiator is full as well as the overflow you have nothing to worry about.

 

[954TalonTsi]

Swapped out the altenator with a new bosch unit, didnt change a thing.... Also swapped out my ecu to the eprom/ecmlink unit that I had after charging the battery, threw no codes.... Me and my uncle are stummped. I could really the advice of a guru as this is my dd and dont have another ride to work .

 

[GRAVEDIGGER]

So are you saying that you have no lights coming on, but you still aren't getting good voltage? Or are you saying that the voltage is good, but you get lights on with the non-eprom ecu?

 

[laserspeeddemon]

Check the pullies.

 

[954TalonTsi]

Even with the eprom in still throwing the alt/rad lights but no cels. And I dont see what the pullies could have anything to do wit it... They spin when cars on, have all four bolts still secured to waterpump shaft. Tomite ima pull entire harness out of car and look very closely at it. This is redicoulse nobodys ever had same problem....

 

[954TalonTsi]

well this is fantastic!! Still having same problems abd cant figure out why. Has anyone ever run a wire from altenator staight to the battery with a cutoff switch incabin?? Seems my only option left unless anyone can help me

 

[steve]

There isn't much to the 1G charging system but it sounds like you haven't looked at the FSM and thought it through.

First stop is reading the troubleshooting section on the charging system in the electrical section of the FSM.

There are three wires for the alternator. The main B+ cable(s) to the alternator stud, the Black/White wire to the L terminal on the connector, and the Yellow wire to the S terminal on the connector. The L terminal connects to the field coil to power it initially and the S terminal is used to sense the voltage of the electrical system.

There are two paths connected to the L terminal from the ignition switch, one through fuse 11 and the charge light in the cluster and the second through a resistor and diode they call the "alternator relay".

OPERATION

When engine is stopped
When the ignition switch is switched to the "ON" position, electricity flows from the "L" terminal of the alternator to the field coil, and at the same time the charging warning light illuminates.

When engine is being started/has started
When the engine is started, charging voltage is applied internally to the "L" terminal of the alternator, with the result that the charging warning light is extinguished since there is no longer any current flowing through the bulb. In addition, because battery voltage is applied to the "S" terminal of the alternator, this battery voltage is monitored at the IC voltage regulator, switching ON and OFF the current to the field coil and thereby controlling the amount of generation by the alternator.

Power is supplied to each load from the "B+" terminal of the alternator.

NOTE
The alternator relay functions as a back-up for the flow of electricity to the field coil if there is a disconnection or damaged wiring of the charging warning light.

TROUBLESHOOTING HINTS
1. Charging indicator light does not go on when the ignition switch is turned to "ON", before the engine starts.
Check the bulb.
Check Fuse 11.
2. Charging indicator light fails to go off once the engine starts.
Check the IC voltage regulator (located within the alternator).
3. Discharged or overcharged battery.
Check the IC voltage regulator (located within the alternator).
4. The charging warning light illuminates dimly.
Check the diodes (within the combination meter and alternator relay) for a short-circuit.

Checking each of the wires for opens, shorts, and other damage goes without saying on a 20 year old car since the wires are located in a high heat area and subject to vibration.


The ECU has no connection to the charging system on a 1G.
The Brake, Radiator, AT Temp (on an auto), and Charge lights all have diodes connecting them to the alternator L terminal. This is for the Bulb Test when you turn the ignition on but they can light if the alternator is not charging.

If the battery is low/dead you won't have enough voltage at the L terminal to energize the field coil to bootstrap the alternator. If the alternator fuse is blown you won't see changing voltage at the battery and if the battery is low could cause the alternator voltage to spike. Same is true if the S wire is damaged.