1994 STS Alternator please help

[tommytom]

ok here is my problem i replaced my alternator in may it is a after market one beck and arnley

#1 I HAVE MY IDLE CONTROL DISCONNECTED BECAUSE IT CLICKS , I DID THE TPS RELEARN STILL CLICKS. I HAD MY IDLE SET ABOUT 1000 RPM , I SEEMED TO HIGH FOR ME SO I TOOK IT DOWN TO ABOUT 600 RPM.

THE NEXT DAY AFTER TAKING THE IDLE DOWN I GET THE MESSAGE "BATTERY NO CHARGE" WHEN I GIVE IT GAS THE MAESSAGE TURNS OFF AT STOP LIGHTS IT KEPT COMMING ON . DROVE ABOUT 100 HIGHWAY MILES OR SO , AND IT DIDNT COME ON ONCE . THEN IT COMES BACK SO I STEP ON IT A LITTLE AND IT TURNS OFF. SO I GO TO THE BATTERY VOLTAGE DISPLAY IT SAYS 13.8 VOLTS , AND AS IAM WATCHING THIS IAM DOING 70 MPH AT ABOUT 2800 RPM IT STARTS DROPING AGAIN AND THEN 10 MILES FROM HOME DIES OUT . SO I BRING IT HOME CHANGE THE BATTERY WITH A NEW DIEHARD GOLD .AND RISE THE IDLE CONTROL TO 900 RPM . DO A PS23 OVERRIDE COMMAND ON ,WAIT 1 MIN AND IT STILL DOESNT TRUN ON THE GENERATOR,

#2. checked all connections grounds and positive terminals

#3. SO I CHECK THE TERMINAL "L" THE GENERATOR WIRE THAT GOES TO THE PCM" "the only wire coming from the genorator regulator"

DISCONNECTED FROM GENERATOR METER READINGS

IGNITION ON BUT NOT RUNNING = 0 VOLTS

IGNITION on and running = 10.001 volts

PS23 OVERRIDE COMMAND OFF = 0 VOLTS

PS23 OVERRIDE COMMAND ON = 10.001 VOLTS

#4 DTC CODES PRESENT

P080 = TPS LEARN , NOT COMPLETE

CODE HISTORY = P110

#5 TEST OUTPUT OF THE GENERATOR AT 2000 RPM IT IS PUTTING OUT 4 VOLTS

QUESTIONS

# 1. IS 10 VOLTS SENT TO "L" TERMINAL FROM PCM , THE RIGHT VOLTAGE TO TELL THE GENERATOR TO TURN ON ?

# 2. CAN I CLEAR THE DTC CODE HISTORY. IS THE CODE PERVENTING THE GENERATOR FROM TURNNING ON?

# 3. IS THE P080 CODE NOT LETTING THE GENERATOR TURN ON ?

thanks any input on this will be greatly aperciated

[MAC]

A shorted diode may cause the P110 code to set. This means there is an L-terminal Circuit Problem. If the generator is making a growling sound it is a result of an electrical imbalance caused by a shorted diode (See 1994 GM Service Manual p. 6D3-8). If a diode is open it will reduce maximum amperage output by 10%. If a diode is shorted it will reduce maximum amperage by 30%.

However, if the generator internal regulator grounds the L-terminal it will cause the ‘BATTERY NO CHARGE’ to be display but it will not cause a code to be set. If the L-terminal does not receive the correct voltage, the voltage regulator will prevent the generator from charging the system. This would fall in line with a possible open or shorted diode. The bottom line is that the PCM is detecting abnormal voltage.

# 1. IS 10 VOLTS SENT TO "L" TERMINAL FROM PCM , THE RIGHT VOLTAGE TO TELL THE GENERATOR TO TURN ON ?

The PCM will initiate generator operation by supplying 12 volts through an internal resistor, to the L-terminal.

# 2. CAN I CLEAR THE DTC CODE HISTORY. IS THE CODE PERVENTING THE GENERATOR FROM TURNNING ON?

No, the code is not preventing the generator from turning on.

# 3. IS THE P080 CODE NOT LETTING THE GENERATOR TURN ON ?

No, the P080 code is not preventing the generator from turning on.

The P080 code is probably due to erratic signals from the Throttle Position Switch or TP Sensor. I suppose erratic signals may also include no signal at all as in being disconnected. Also, this code may be set by erratic, rough or unstable idling.

When you checked the battery cables does this mean you inspected the positive side cable under the red plastic insulation? If you see any acid buildup or corrosion clean it thoroughly. The Northstar electrical system is very sensitive to corroded battery connections. In fact, I wouldn’t be surprised if the TPS problems are related to battery cable corrosion. According to GM’s Service Manual corroded battery cables is the first thing to look for when performing a “GENERATOR FUNCTIONAL CHECK” (p. 6D3-9).

[Ranger]

FWIW, I once recall someone on this board having a similar problem. After returning the aftermarket alternator and puting in an A/C Delco alternator, his problems were solved.

[mcnu]

i have a similar problem with my 98 eldorado. the alternator went out. i replaced it with a autozone one. it went out about a month later. luckily, i save the original one out of the car, and had it rebuilt. however, when, it went out the second time, the battery not charging light came on. it now stays on, but will go off here and there, like at a stop light, and then come back on. i have been driving the car for over a year like this, so i know that the alternator is charging the car. i just did the grabbed the codes from the DTC and got PCM P1483, ACM B1983 and IPC B1911. can anyone shed some light on how to get the battery not charging off the dash. thanks in advance.

[MAC]

i have a similar problem with my 98 eldorado. the alternator went out. i replaced it with a autozone one. it went out about a month later. luckily, i save the original one out of the car, and had it rebuilt. however, when, it went out the second time, the battery not charging light came on. it now stays on, but will go off here and there, like at a stop light, and then come back on. i have been driving the car for over a year like this, so i know that the alternator is charging the car. i just did the grabbed the codes from the DTC and got PCM P1483, ACM B1983 and IPC B1911. can anyone shed some light on how to get the battery not charging off the dash. thanks in advance.

The key code to look at here is the IPC B1911, which is refers to a problem with the altenartor's "L" Terminal. If the altenator is rebuilt then maybe you should swap it for a new ACDelco or take your chances with a new one built by a reputable manufacturer. The bottom line is that rebuilt alternators can be nothing but trouble. I went through 4 rebuilt altenators when I owned a '94 Eldorado and I finally bought a brand new one which solved the problem. However, it could be connections to the alternator are loose or something isn't right there or the belt is loose since the problem is intermittent. If connections and belt are good, then the cause is likely the altenator. But check the connections and belt and you may just solve the problem.

[winterset]

Make sure all your battery terminals are clean, and inspect all the wiring, and even the underside of the fuse panels for corrosion. I too would be suspect of aftermarket alternators, but there can be other causes. could be aftermarket are more sensitive to "other" electrical conditions in the circuits. When my battery was going bad, I was getting the "BATTERY NO CHARGE". I changed the battery, and all was fine.