went to the store the other day and came out to my 97 tj not starting. nothing happened all no lights no turning over nothing, my buddy came out and jumped it and i was on the road again but noticed that my volt gauge was spiking at 19, so i pulled over and checked to make sure everything was fine and everything looked fine. got to my buddies house and shut it down then tried to restart it again and the same thing, nothing. i replaced the alternator and put a new battery in it and $230 later the same thing. i'm p***ed off cause thats what oriellys told me was wrong and just seems like im being lied to. can anyone help with this issue im having?
electrical bug strikes hard
- Thread starter jbjeeper
- Start date
JPNinPA
Well-known member
Well those would be two of the three or so things I'd check first. Did they check the alternator or battery for you? O's, Advanced and the other one I can't seem to think of will check the battry and alternator for you for FREE.
Check your grounds from Battery to chassis, alternator to chassis and engin to chassis. Other than this the PCM has the alternators regulator in it and may be going. i don't know how to check it though.
Hope this helps.
Check your grounds from Battery to chassis, alternator to chassis and engin to chassis. Other than this the PCM has the alternators regulator in it and may be going. i don't know how to check it though.
Hope this helps.
had the altanator checked and first one was bad so i replaced it. Didnt fix a thing so then i figured battery. Got the new battery installed, went to fire... boom nothing. I talked to a friend and he said voltage regulator, called the parts store and was told thats inside the altanater. Once again i am lost. Any other ideas on what this problem could be caused by? Or can anyone explain where this PCM is? is it one of the wires connecting to the alternator?
JPNinPA
Well-known member
Is the alternator you purchased a direct replacement? If not the extra regulator may be causing an issue.
The PCm is the "computer" that monitors your engine. It is the thing behind the battery and on the firewall with a few cable connectors comming off it. It's not cheap so we'd want to be sure this is it prior to just changing it.
I'd also check for a short somewhere and possibly get teh starter checked. Your origional issue was not starting. How to check for shorts. Disconnect teh battery positive terminal and place a multi meter that could read current in line withthe pos term and pos cable connector and read teh current. Anything higher than 10-20 mA you may have an issue.
The PCm is the "computer" that monitors your engine. It is the thing behind the battery and on the firewall with a few cable connectors comming off it. It's not cheap so we'd want to be sure this is it prior to just changing it.
I'd also check for a short somewhere and possibly get teh starter checked. Your origional issue was not starting. How to check for shorts. Disconnect teh battery positive terminal and place a multi meter that could read current in line withthe pos term and pos cable connector and read teh current. Anything higher than 10-20 mA you may have an issue.
SteelHeadz
Super Moderator
The voltage regulator is inside the PCM. The alternator does not regulate the voltage on how much to charge the battery depending on load and temperature. One thing to check is the battery temp. sensor located under the battery on the tray. Make sure it's hooked up and not shorted to anything. The charging system is turned on and off with the ignition switch. When the ignition switch is turned to the ON position, battery voltage from the powertrain control module (PCM) is supplied to the generator rotor to produce a magnetic field. This is done through one of the two field terminals at the rear of generator. On Jeep models of previous years, battery voltage to this field terminal was supplied from the ASD relay.
The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry contained within the PCM. This circuitry is connected in series with the second rotor field terminal and ground.
A battery temperature sensor, located in the battery tray housing, is used to sense battery temperature. This temperature data, along with data from monitored line voltage, is used by the PCM to vary the battery charging rate. This is done by cycling the ground path to control the strength of the rotor magnetic field. The PCM then compensates and regulates generator current output accordingly.
All vehicles are equipped with On-Board Diagnostics (OBD) All OBD-sensed systems, including the EVR (field control) circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC) The PCM will store a DTC in electronic memory for any failure it detects. Refer to On-Board Diagnostic Test For Charging System in this group for more information.
The Check Gauges lamp monitors the Voltage, Engine Coolant and Engine Oil Pressure gauges. The lamp is located on the instrument panel. If any of the three gauges detects an extreme condition, the lamp will be illuminated. This is done as reminder to check the three gauges. The signal to activate the lamp is sent via the CCD bus circuits.
INSPECTION
These tests will show the amount of voltage drop across the generator output wire, from the generator output (B+) terminal to the battery positive post. They will also show the amount of voltage drop from the ground (-) terminal on the generator to the battery negative post. A typical generator wiring harness is shown in Generator Terminals (Typical Wiring Harness Shown) Wiring harness routing as shown in Generator Terminals (Typical Wiring Harness Shown) may be slightly different depending on vehicle model and/or engine. Refer to Wiring Diagrams for additional information.
A voltmeter with a 0 - 18 volt DC scale should be used for these tests. By repositioning the voltmeter test leads, the point of high resistance (voltage drop) can easily be found.
PREPARATION
I hope this helps.
The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry contained within the PCM. This circuitry is connected in series with the second rotor field terminal and ground.
A battery temperature sensor, located in the battery tray housing, is used to sense battery temperature. This temperature data, along with data from monitored line voltage, is used by the PCM to vary the battery charging rate. This is done by cycling the ground path to control the strength of the rotor magnetic field. The PCM then compensates and regulates generator current output accordingly.
All vehicles are equipped with On-Board Diagnostics (OBD) All OBD-sensed systems, including the EVR (field control) circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC) The PCM will store a DTC in electronic memory for any failure it detects. Refer to On-Board Diagnostic Test For Charging System in this group for more information.
The Check Gauges lamp monitors the Voltage, Engine Coolant and Engine Oil Pressure gauges. The lamp is located on the instrument panel. If any of the three gauges detects an extreme condition, the lamp will be illuminated. This is done as reminder to check the three gauges. The signal to activate the lamp is sent via the CCD bus circuits.
INSPECTION
- Inspect condition of battery cable terminals, battery posts, connections at engine block, starter solenoid and relay. They should be clean and tight. Repair as required.
- Inspect all fuses in the fuseblock module and Power Distribution Center (PDC) for tightness in receptacles. They should be properly installed and tight. Repair or replace as required.
- Inspect the electrolyte level in the battery. Replace battery if electrolyte level is low.
- Inspect generator mounting bolts for tightness. Replace or tighten bolts if required. Refer to the Generator Removal/Installation section of this group for torque specifications.
- Inspect generator drive belt condition and tension. Tighten or replace belt as required. Refer to Belt Tension Specifications in Group 7, Cooling System.
- Inspect automatic belt tensioner (if equipped) Refer toCooling System for information.
- Inspect connections at generator field, battery output, and ground terminals. Also check ground connection at engine. They should all be clean and tight. Repair as required.
These tests will show the amount of voltage drop across the generator output wire, from the generator output (B+) terminal to the battery positive post. They will also show the amount of voltage drop from the ground (-) terminal on the generator to the battery negative post. A typical generator wiring harness is shown in Generator Terminals (Typical Wiring Harness Shown) Wiring harness routing as shown in Generator Terminals (Typical Wiring Harness Shown) may be slightly different depending on vehicle model and/or engine. Refer to Wiring Diagrams for additional information.
A voltmeter with a 0 - 18 volt DC scale should be used for these tests. By repositioning the voltmeter test leads, the point of high resistance (voltage drop) can easily be found.
PREPARATION
- Before starting test, make sure battery is in good condition and is fully-charged. See Battery for more information.
- Check condition of battery cables at battery. Clean if necessary.
- Start the engine and allow it to reach normal operating temperature.
- Shut engine off.
- Connect an engine tachometer.
- Fully engage the parking brake.
- Start engine.
- Place heater blower in high position.
- Turn on headlamps and place in high-beam position.
- Turn vehicle interior lamps on.
- Start engine. Bring engine speed up to 2400 rpm and hold.
- Testing (+) circuitry:
- Touch the negative lead of voltmeter directly to battery positive post.
- Touch the positive lead of voltmeter to the B+ output terminal stud on the generator (not the terminal mounting nut) Voltage should be no higher than 0.6 volts. If voltage is higher than 0.6 volts, touch test lead to terminal mounting stud nut and then to the wiring connector. If voltage is now below 0.6 volts, look for dirty, loose or poor connection at this point. Also check condition of the generator output wire-to-battery bullet connector. Refer toWiring for connector location. A voltage drop test may be performed at each (+) connection in this circuit to locate the excessive resistance.
- Testing (-) circuitry:
- Touch the negative lead of voltmeter directly to battery negative post.
- Touch the positive lead of voltmeter to the ground terminal stud on the generator case (not the terminal mounting nut) Voltage should be no higher than 0.3 volts. If voltage is higher than 0.3 volts, touch test lead to terminal mounting stud nut and then to the wiring connector. If voltage is now below 0.3 volts, look for dirty, loose or poor connection at this point. A voltage drop test may be performed at each (-) connection in this circuit to locate the excessive resistance. This test can also be performed between the generator case and the engine. If test voltage is higher than 0.3 volts, check for corrosion at generator mounting points or loose generator mounting.
I hope this helps.
did you check the ground yet? I am kinda leaning towards this but...
I had an assumed voltage regulator issue on my jeep, it's older and has a different system, but mine would spike to about 18 volts and would blow the ignition fuses constantly. ended up being one od the field wires on teh back of the aqlternator was just a little deteriorated, cleaned it up, new terminal, no problems since (about 6 years ago)
I had an assumed voltage regulator issue on my jeep, it's older and has a different system, but mine would spike to about 18 volts and would blow the ignition fuses constantly. ended up being one od the field wires on teh back of the aqlternator was just a little deteriorated, cleaned it up, new terminal, no problems since (about 6 years ago)
so i pulled all my grounds off the other day and sarted cleaning them with sand paper. none of them looked real bad but i cleaned them anyways, replaced the end running to my starter and cut the negative terminal off and replaced it with 2 new ends.i also replaced my chassis ground running to the firewall, i sanded the spot down to get a good metal contact. she fired right up and is running better then ever, just wish i hadnt taken my core back for the alternator cause they screwed me outa $130. you guys are the **** thanks.
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