Question about 1998 GMC Sonoma

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Is my PCM going bad? charging system works ok until engine warms up then the meter show inadequate charging

Alternator removed and bench tested ...ok. Terminals are clean no wires appear ballooned (from internal corrosion.

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  • 513 Answers

CK SERPINTINE BELT TENSIONER ,IF IT IS NOT MANTAINING CORRECT TENSION ON BELT IT WILL SLIP AT HIGHER RPM, ALSO CK BATTERY ,BAD CELL CAN CAUSE THIS ISSUSE

Posted on Nov 20, 2014

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6ya6ya
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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

  • 375 Answers

SOURCE: diagram of Igniton system 1987 gmc v1500 4x4

I own a shop, and think this; If you have a Chilton's Repair Manual, you can go to the back of the book, and locate the typical wiring diagram for most all GM vehicles. They are basically the same on all of them. I know the Haynes Manual has these in the back pages, so look there first. I have a feeling you have not got the neutral safety switch wired up. There should be a yellow wire that comes from the ignition switch that goes to this switch. The switch is located under the dash near the clutch linkage on a straight drive, and on the transmission for an automatic. There should be a purple wire that comes from this switch that goes to the starter solenoid. It should have power on it "only" when the ignition switch is turned to the start position, and the neutral safety/clutch start switch is activated. This switch may be out of adjustment, and not sending any power to the starter solenoid. This wire should hook on the terminal that is closest to the engine block. The other wire will have power on it all the time when the ignition switch is in the on position, and should hook to the (hold in winding) on the other side of the solenoid. You may be loosing power, or not have any power on the purple wire that activates the (pull in winding that is closest

Posted on May 18, 2008

  • 8 Answers

SOURCE: Is there a switch or relay that kicks on/off the

sounds like the battery has a dead cell in it. i would get a new battery.

Posted on Jan 31, 2010

  • 752 Answers

SOURCE: wont start--pulled starter bench tested ok

check your ignition did one of these before changed 3 starters before finding out it was ignition switch not making connection in switch good luck

Posted on Feb 07, 2010

  • 52 Answers

SOURCE: battery not charging sign displayed , voltage

Go to autozone or whatever auto parts store is close to you and have them check your charging system. Most places do this for free and they can determine exactly what part you need to replace.

Posted on Dec 12, 2010

redds55
  • 2620 Answers

SOURCE: 2007 Yukon Denali system charging problem. I had

Its the alternator,if you don't have 14-14.6 volts with engine running its the alternator.

Posted on May 15, 2011

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3 Answers

2004 ford freestar 4.2l Not charging, new alternator tested and working new battery.


Hotrod, Recheck,clean and tighten all connections. If you say you had new alternator tested and is working OK, the new battery must be defective. With the van running, use a DVO meter and check the battery, if it shows above 14 volts then the alternator is OK, a good battery should show 12.4, that leaves either a faulty battery not holding a charge or you have a parasitic draw(something draining battery). Which would have to be diagnosed by a good Tech.
Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
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May 25, 2016 | Ford Cars & Trucks

1 Answer

Alternator?


I would say that you have a bad battery . If the alternator is charging ok but the battery is bad all the current will go to the dying cell . Have a load test done on the battery to eliminate it as a source of a problem. Next have the alternator bench tested as there may be a problem in the rectifier pack

Mar 19, 2014 | 1995 Chevrolet Caprice Classic

1 Answer

2002 kia Rio Altenator not chargeing ( alt light not showing discharge ) Changed alt, Check out put with volt meter still putting out only 12.2 should be 13.8 Alt checked out OK on bench...


Hi, the actual output voltage produced by the alternator will vary depending on temperature and load, but will typically be about 1-1/2 to 2 volts higher than battery voltage. At idle, most charging systems will produce 13.8 to 15.3 volts with no lights or accessories on. This can be measured by connecting the positive (+) and negative (-) test leads of a voltmeter to the battery posts while the engine is running.

Possible cause of the alternator not charging includes Slipping or broken alternator belt, Open diode, Open circuit in stator windings, Open charging circuit, Open field circuit, Worn brushes or slip ring and Defective voltage regulator..

Feb 27, 2011 | Kia Rio Cars & Trucks

1 Answer

Have a 2004 saab aero 9-3. Recently battery died. It was shorted. But 6 years old. Replaced battery. Now often when trying to start, makes one loud click and won't start. Displays flicker and/or go black,...


I was having the same problem with my 2004 9-3. I assumed the starter was bad and replaced it. I then charged the battery and found it wouldn't fully charge. After charging for several hours when I removed the charger I only showed 11 volts at battery posts. The new battery tested 12.8 volts and the car started well. With the car idling I tested and showed 14.6 volts at the battery post which confirmed my alternator was charging.

I do believe I replaced the starter in error and that it was just a bad battery. When my battery was failing I had dim headlights and flashing displays that you described and the clicking noises also. When I put jumper cables on my saab and let the bad battery charge for several minutes the car would start right up and the headlights would brighten up and even though the battery was bad the idle voltage at the battery posts was increased to 14.6 volts coming from the alternator.

Remember to remove the jumper cables quickly once the car starts to avoid possible electrical problems.

I have had bad starters in other vehicles that would draw a huge load on the battery and jump starting them would sometimes give enough voltage to turn the engine over and start it.

Bench tests aren't always correct because the components aren't under a true load. I had a brand new alternator fresh out of the box last year that was bad and wouldn't put out good voltage even though it bench tested perfect. Go figure.

Check your battery voltage with the engine off. It should read over 12 volts if its charged.

Sep 05, 2010 | Saab 9 3 Cars & Trucks

2 Answers

Battery won't charge when car is on. Battery is fine. Believe it's a problem with the wiring


If the alternator has been bench tested and passed then you need to check the big wire for 12volts at the alternator. If you have 12 volts then you need to trace the other wire to the PCM. The charging system is computer controlled and its possible the computer is the issue. To diagnose this correctly go to mitchell1diy online and pay the ten bucks for all the proceduers and wiring diagrams. If the charging system light is off then try this. Charge up the battery. Then turn the lights on for a couple minutes to drain the surface charge. Then using a 12v meter hooked to the battery check the draining voltage while cranking. A good battery will maintain a 12 or better voltage even if the truck does not start. If it goes down fast then the battery is bad. Alot of times when a battery is tested using a professional tester they pass. You may need to remove the fuel pump relay so the truck does not start for this test since your testing the cranking amps. Also with the key out of the ignition and doors locked and the negative unhooked at the battery you can check for parasitic drain. Using a amp meter hooked up inline battery to cable you should have less than 1/10th volt. If any more then you have a component not shutting off. Pull fusses 1 at a time till you find the system thats the issue. Watch the meter as you pull fuses

Jun 08, 2010 | 2001 Ford Ranger Regular Cab

1 Answer

Over chargeing up to 16.8 volts, two bench tests of alternator says it is ok


How are you measuring the 16.8 volts? Is this what your cars readout or gauge reads? Maybe gauge bad. Or are you measuring with a volt meter at battery with engine on? Then regulator on alternator has to be bad. After you drive car is battery overheated? If you look inside battery is it almost boiling? Bad alternator regardless of tests.

Mar 15, 2010 | Cadillac Eldorado Cars & Trucks

1 Answer

Alternator problem?


check battery voltage with engine off. should be @ 12.5v
check with engine running at about 1500 rpms. It should be @ 14 volts. If yes, it is ok. I think you are ok.
Please rate higly if htis helps

your system is more sophisticated than Sars can handle.

here's how it works.

The charging system consists of a generator which generates current to supply the vehicle electrical system and maintain the battery in a charged condition.
The generator is driven by the accessory drive belt. For additional information, refer to Section 303-05 . When the engine is started, the generator begins to generate alternating current (AC) which is converted to direct current (DC) internally. The DC current is controlled by the voltage regulator (located on the back of the generator), and then supplied to the battery.
The charging system voltage is controlled by the powertrain control module (PCM). The generator charges the battery and at the same time it supplies all the electrical loads that are required. The battery is more effectively charged with a higher voltage when the battery is cold and a lower voltage when the battery is warm. The PCM is able to adjust the charging voltage according to battery temperature by using a signal from the intake air temperature (IAT) sensor. This means that the voltage setpoint is calculated by the PCM and communicated to the regulator by a communication link.
The PCM simultaneously controls and monitors the output of the generator. When the current consumption is high or the battery is discharged the system is able to increase the idle speed.
To minimize the engine drag when starting the engine, the PCM controls the generator. The generator does not produce any output until the engine has started. The PCM then progressively increases the output of the generator.
The PCM controls the operation of the charging system warning indicator in the instrument cluster. The PCM is therefore responsible for turning the warning indicator off after the engine is started and illuminating it under fault conditions (when the generator is not generating the correct amount of current with the engine running). The warning indicator will also be illuminated by the PCM at key - on engine off and stall conditions.

May 10, 2009 | 2006 Ford Focus

4 Answers

Put a new alternator in 2000 Jeep Grand Cherokee engine light on


well , the ECU runs the alternator. (DG wire "dark green")
the alternator field is controlled 100% by PCM reg , inside PCM.
so..... if the running engine has 13.3, to 15vdc the alt is working
if lower, its not. (rpm on engine 800 or more)

not scanning the PCM a the CEL glow, you missed the boat.
why not scan it. see why the PCM is upset (DTC errors stored)

see the 2 lower pins below , those go to PCM.
in theory if the field in the old BAD ALT, was shorted.
that could in fact, burn up the PCM regulator.
shorting outputs of PCM , does that in most cases.
im the poor sod that fixes PCM's.so....

1946421-gyllgess1dmtl30sgxtyvqv2-3-0.jpg

Apr 07, 2009 | 2000 Jeep Grand Cherokee

1 Answer

Will not start


Have your battery charged and load tested to make sure it's OK. Then check the charging system and alternator drive belt for tension and condition. If car won't staqrt after charge, you may need to remove alternator to have it tested on a bench. Otherwise, put a volt meter across both terminals. With engine off, volts should be 12 or higher. Running should be 13,5-14V running with all lights, heater and A?C on should not drop lower than 12.8v.Low readings running indicate a bad alternator. If everything in charging system checks out OK, problem is likely in the starter or starter relay.

Mar 31, 2009 | 1999 Pontiac Grand Am GT

1 Answer

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.)))

Feb 18, 2009 | 1998 Chevrolet Monte Carlo

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