Question about GMC Sierra 1500

Open Question

Where is the PCM located on my 2001 GMC Sierra PU

The battery light started going on and off, but voltage was always over 14V. Than I noticed the voltage also droped. The next morning it was once again over 14V, about 14.5V with the battery light going on and off at will, after about 45mins. the voltage droped once again to about 12V. Load tested the battery and it passed. Replaced the alternator with a rebuilt unit. Still have the same problem. Any advise would be great !

Posted by on

  • Raymond Groff Dec 09, 2012

    I have checked all the conections at the alternator and they are all tight and clean,where is the PCM located so I can check that conection ?

  • Raymond Groff Dec 09, 2012

    Does the alternator need a field voltage to excite the windings ?

×

Ad

3 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of.(from cars to computers, handyman, and even drones)
click here to download the app (for users in the US for now) and get all the help you need.
Goodluck!

Posted on Jan 02, 2017

Ad
localwonder
  • 6784 Answers

SOURCE: 1998 Monte Carlo alternater not charging

Ok, i understand that you have replaced the alternator, but there seems to be a non charge state in this case. i recommend checking the charging system. use the procedure below to isolate this issue.

Wear protective eye wear and clothing and remove all jewelry when checking your battery and charging system. Jewelry is a good conductor of electricity and is not recommended. Most batteries wear out every 3 to 5 years and need to be replaced. Always replace your battery with an equal replacement battery to assure proper operation. Automotive batteries have a +positive terminal (red), - negative terminal (black). The battery in this illustration has a protective cover over the positive terminal to prevent short circuit in case of an accident. Electricity is stored in the battery and then supplied to the vehicle when the engine is not running. While the engine is running the vehicles alternator charges the battery for future use. (Note: never disconnect the battery while the engine is running. If the battery cable is disconnected from the battery a spark can be generated which can cause the battery to explode or a major electrical malfunction to occur.)

To check a battery surface voltage, remove the positive terminal protective cover. Connect the +positive side meter lead (red) to the positive side battery terminal. Connect the - negative (black) side meter lead to the negative battery terminal. With the vehicle not running and the car sitting over night the battery voltage should be between 12.5 and 12.8 volts.(You will need to use a voltmeter for this testing procedure)

The alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.(most non charge states will be the cause of a loose belt or a low tension rate, due to a mis-adjusted alternator. make sure you have enough tension in the belt for full rotation of the alt pulley)

Next, you will need to check the alternators output with the Amp meter.

Testing the amperage output of the alternator is good for measuring the amount (not the level) of voltage the alternator can produce. This test can be tricky because if the alternator is weak it can still show it as producing amperage. Which is good, but if the voltage is low, it will still allow the battery to go dead. To check the amperage output of an alternator an amp meter is needed. Once the meter is connected start the engine. Next turn on all electrical accessories and raise the engine idle to about 1200 RPM. The alternator should output the max amperage it was designed to produce. Example: a 90 amp alternator should output about 88 amps. Note: An alternator cannot sustain maximum output for long periods of time. If the alternator is forced to operate at maximum output it will overheat and fail. An alternator is designed to operate at max amperage output only for a reasonable amount of time.

((Connect the voltage meter lead the same way you would in a battery static voltage check, Start engine (do not drive) at engine idle the voltage should be between 13.6 to 14.3 volts. If not the alternator may need replacing.)))

Posted on Sep 07, 2009

Ad
  • 52 Answers

SOURCE: '91 Integra Battery light on, alternator OK

Check for worn electrical part of your ignition switch. Often when a large amount of keys dangle from the switch it can wear out the plastic switch over the years. With car running wiggle the ignition key as if the keys are danging when driving to see if these lights come on again.

Posted on Sep 25, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

I have a 2001 GMC sierra denali 6.0 2500. replaced the starter and took battery out to recharge it and now truck starts then dies right away like it is not getting fuel


Anti-theft light lit on the instrument cluster (SECURITY) .
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent is provided in order to prevent the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the lock cylinder. The cylinder rotation produces an analog voltage code in the Passlockā„¢ sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a class 2 message is sent from the BCM to the powertrain control module (PCM)/vehicle control module (VCM). The message enables the fuel injectors.

Nov 08, 2017 | GMC Safari Cars & Trucks

1 Answer

My 2004 GMC sierra Denali pickup battery drains


After you get the truck started disconect you battery cable and see if the truck continuse to run. if it dies you are having a problem with the charging system. make sure dont have any interior lighs left on.

Mar 05, 2013 | 2004 GMC Sierra Denali

1 Answer

Alternator wont charge


at alternator gig wire battery voltage,one wire battery volts one less . battery volts wire goes to automatic shut down relay, less then battery voltage wire to pcm fuse will be 20 amp just ck all that size.

Aug 05, 2012 | 2001 GMC Sierra 2500HD

3 Answers

2001 gmc sierra 1500. Battery light in msg center binks on and off. Voltage is fine. Battery is fine. Altenator is fine. Voltage regulator maybe?? Not sure if its located on the altenator or in the...


The regulator is in the alternator. Did you check voltage at the battery? Nothing in the diagram jumps out at me. Is the check engine light on? Maybe we could get a hint if there was a trouble code.bc11b1d.gif

Sep 26, 2010 | 2002 GMC Sierra 1500

1 Answer

2001 honda odyssey, will a passenger sliding door that is not fully engaged drain the battery? I noticed it was slightly out at the back and the car won't start although I have the inside light switch to...


Will the car start from a jump? If so then have the voltage checked while the engine is running, should be something like 14v. If that's ok then I'd say its still the battery. Have you had cold weather? That's a mjor source of battery death.

Jan 06, 2010 | 2001 Honda Odyssey

1 Answer

Battery light just came on but it cant be my alt because it still starts and drives around town ive drivin across the city and back twice and had the lights on didnt die started when shut off?


The battery light trips when it detects an issue with the charging system. Very rarely, the battery light can trip if there's an issue with the PCM, but this is very rare.

Take a voltmeter with the car off and measure the voltage on the leads of the batter, should be around 12V+-.2. With the car running, measure again and this time it should read 13V-14V. If it does read 13V-14V then it means that the alternator is working. If it is below 12V, then it means your alternator is not charging the battery properly. If it's above 14V, then it means your alternator is overcharging and damaging the battery.

Oct 22, 2009 | 1998 Lincoln Town Car

1 Answer

Wife turned off GMC Sierra & removed key when not in park gear


hold foot on brake pedal try turning key to on position to put truck all the way in park.

May 31, 2009 | 2001 GMC Sierra 1500HD

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

64 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts

yadayada
yadayada

Level 3 Expert

76846 Answers

Freddy

Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22246 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...