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1999 Isuzu Trooper Alternator Gremlins

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3.6K views 10 replies 3 participants last post by  Buster28  
L
#1 ·
First timer :alien:
Have been reading the planet Isuzu for 4 years. i enjoy the site and information that is shared.
Have enjoyed many year of great service in our 1999 Isuzu trooper 3.5
Problem that i am working on today. Battery and brake light in instrument panel were coming on only some times when engine RPM went before 1200. Not always.
Note: when battery and brake indicator lamps were on. You would hear relays clicking under dash panel near drivers door. Blower and AC would turn off. Trooper would also kill sometime. However would start right back up.
It never failed to start.
Not shore if the two R related Transmission.
when you put gear selector in drive there is a delay before you feel a bump. the Bump is new. the trooper will drive fine after that. The delay is only noticed when you put into for Park, Reverse, Neutral you can stop in traffic and return to speed no problems
back to Alternator
Replace Alternator, tried to start battery was dead. put charger on battery over night. still would not start.
went to auto supply house they gave me a new battery.
Put new battery in to trooper it fired right up.
Put volt meter on battery voltage is dropping.
 
#2 ·
LafHonda250 said:
Put volt meter on battery voltage is dropping.
Click to expand...
If the alternator is working properly the voltage across the battery terminals with the engine running at idle is about 14.4 Vdc. A fully charged battery is about 12.6 Vdc. If you read less than this across the battery terminals and the voltage is dropping the alternator is not charging the battery. When the battery voltage drops below 8 Vdc the engine will start to run ragged and the transmission won't shift properly because the PCM supply voltage is too low.
 
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#4 ·
The White/Blue goes to the PCM, the Blue/Yellow goes to the Ignition Switch and the White/Green goes to the Charge Warning lamp and the Heater/AC relay.

The White/Blue allows the PCM to turn Off the Alternator under certain load conditions.
The Blue/Yellow provides +12 Vdc to operate the voltage regulator and excite the alternator rotor winding.
The White/Green energizes the Heater/AC relay to allow the Blower Motor to operate when the alternator is producing current. If the alternator Is Not producing current it provides a path to ground to illuminate the Charge Warning lamp.
 
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L
#5 ·
? What is the PCM and its location.
If I removed the Wht /Blu wire from alternator than alternator may start to put out 14.8 volts. At this time when engine is running voltage being measured is that of the battery.
The wire r discolored so
Pin arrangement : from voltage regulator engine side to wheel well side.
Thanks in advance .
 
#6 ·
The PCM is the Powertrain Control Module, it is the engine and transmission "computer". The PCM located above the center console as shown in the attached image. It has 3 cables and connectors.

I don't understand the rest of your question(s).
 

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J
#7 ·
LafHonda250 said:
? What is the PCM and its location.
If I removed the Wht /Blu wire from alternator than alternator may start to put out 14.8 volts. At this time when engine is running voltage being measured is that of the battery.
The wire r discolored so
Pin arrangement : from voltage regulator engine side to wheel well side.
Thanks in advance .
Click to expand...
The wires are discolored? like they have been hot but not hot enough to melt? check the connections for corrosion. I believe the excitation wire is required for the alternator to charge. at least thats the case on other makes models I have seen.
 
L
#8 ·
Mr Buster, Thanks
To confirm that the PCM was preventing the alternator from generating any power. Battery voltage before I started engine 12.5VDC. To test cut Wht/Blu wire. After disconnecting and isolating. With engine idling battery voltage 14.7.
So now PCM is the source of the problem.
Is there a method to reset this code (alarm).
Is there a method to field test and read PCM codes. As well as a code description source.
Thanks.

Is there anything I can still do before bring
 
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