2004 Explorer Charging System Failure

[Geologist]

Hello Everyone,

The project truck is a 2004 EB Explorer 4WD.

The problem is as follows:

Start the truck and the red battery light comes on with the "Check Charging System" message.

Occasionally when you start the truck it will charge for about 5 minutes, then back to no charging.

Verified with my multi meter it is not charging so have already done the following:

1: New Alternator.
2: New Battery.
3: New 3 pin alternator connector.
4: New connector on the extra alternator pin.
5: Deleted the fusible links (all).
6: Ran new wires from 3 pin alternator connector all the way to their destinations.
7: New Positive cable.
8: Verified good connectivity of negative battery cable.

I have NOT changed the 2-Gauge wire that runs from the alternator to the battery box (ran out of money).

And the problem has not changed at all. It does the exact same thing as the day it first quit charging. Sometimes (very rarely) will charge for no more than 5 minutes, then just stops charging.

Any help with the problem would be greatly appreciated as I am now broke from replacing everything, and need this rig back on the road.

Thanks for looking.

 

[imp]

Hello Everyone,

The project truck is a 2004 EB Explorer 4WD.

The problem is as follows:

Start the truck and the red battery light comes on with the "Check Charging System" message.

Occasionally when you start the truck it will charge for about 5 minutes, then back to no charging.

Verified with my multi meter it is not charging so have already done the following:

1: New Alternator.
2: New Battery.
3: New 3 pin alternator connector.
4: New connector on the extra alternator pin.
5: Deleted the fusible links (all).
6: Ran new wires from 3 pin alternator connector all the way to their destinations.
7: New Positive cable.
8: Verified good connectivity of negative battery cable.

I have NOT changed the 2-Gauge wire that runs from the alternator to the battery box (ran out of money).

And the problem has not changed at all. It does the exact same thing as the day it first quit charging. Sometimes (very rarely) will charge for no more than 5 minutes, then just stops charging.

Any help with the problem would be greatly appreciated as I am now broke from replacing everything, and need this rig back on the road.

Thanks for looking.

Very interesting problem, and you seem knowledgeable about what can be done. I drive an '04 so have Ford wiring diagrams. The dashboard light is in the voltage regulator circuit. The alternator "I" terminal connects to the PCM (computer), which sends the appropriate signal to the instrument panel, which contains the light. Unfortunately, all the action is done digitally, via the CAN bus, and the I.P. is a microprocessor which controls the light. So, we can't mess with the hardware like years ago. I suspect, but cannot confirm, that something is haywire possibly in the wiring which is connected between the PCM and dashboard panel. It consists of a twisted pair of wires. I would try replacing that pair of wires, or at least checking their connections at the PCM and I.P. imp

EDIT: Also, of course, check for trouble codes!

 

[Geologist]

Thanks for the reply imp.

My manual only covers 2002-2003 (bought it when I had an '02).

Is there any way you could scan or photo the wiring diagram of the charging system for me? If not maybe just call out the 2 wire colors under the dash so I can replace them.

I should have mentioned that I have checked the codes and there are none.

Thanks again!

 

[imp]

Thanks for the reply imp.

My manual only covers 2002-2003 (bought it when I had an '02).

Is there any way you could scan or photo the wiring diagram of the charging system for me? If not maybe just call out the 2 wire colors under the dash so I can replace them.

I should have mentioned that I have checked the codes and there are none.

Thanks again!

Sure! If you don't mind waiting till tomorrow. Falling asleep at the stick here. imp

 

[Tech By Trade]

If you want to rule out the 2 gauge wire, disconnect it at the battery and alternator. Take your multi-meter and measure the resistance on ohms from either end of the wire to bare chassis metal to make sure there isn't a short to ground. it should read infinite resistance. Then measure resistance from one end of the wire to the other, it should read 0 to a few ohms, 1 or 2. If that's the case the wire is good and its something else.

 

[imp]

Thanks for the reply imp.

My manual only covers 2002-2003 (bought it when I had an '02).

Is there any way you could scan or photo the wiring diagram of the charging system for me? If not maybe just call out the 2 wire colors under the dash so I can replace them.

I should have mentioned that I have checked the codes and there are none.

Thanks again!

Charging System 2004 Explorer:

 

[Geologist]

Thank you again imp.

Using the diagram you uploaded I replaced the CAN wires but still no change.

Circuit 904 (LG/RD wire) from alternator reads 11.96 Volts when engine is running.

The CAN circuit is outputting about 250 mV.

I may try replacing the Pink/Black wire that goes to the central junction box, but its looking like the dash will need to be removed for that.

The 03 service manual says:

"Measure resistance between the I-Line and ground through the PCM" ... should be 100 ohms or the PCM is bad.

Is this the same in the 04 manual?

Do you happen to know where I would measure the I-line to (from PCM pin 24 to Battery positive for example?)

Thanks again.

 

[imp]

Thank you again imp.

Using the diagram you uploaded I replaced the CAN wires but still no change.

Circuit 904 (LG/RD wire) from alternator reads 11.96 Volts when engine is running.

The CAN circuit is outputting about 250 mV.

I may try replacing the Pink/Black wire that goes to the central junction box, but its looking like the dash will need to be removed for that.

The 03 service manual says:

"Measure resistance between the I-Line and ground through the PCM" ... should be 100 ohms or the PCM is bad.

Is this the same in the 04 manual?

Do you happen to know where I would measure the I-line to (from PCM pin 24 to Battery positive for example?)

Thanks again.

Sorry to take so long. I will have to research this more. Meanwhile, above it states that PCM should be placing 8-9 V on ckt. 904. Is that where you measured 250 MV? If you are measuring voltage across the CAN bus itself, that value will not help us, I think. If you haven't done so, check 904 voltage between 904 and ground, engine running. If you find other than 8-9 V, the PCM is not enabling the alternator regulator.

"Measure resistance between the I-Line and ground through the PCM" ... should be 100 ohms or the PCM is bad."

I am not sure how the above could be accomplished. The PCM is capable of grounding 904 under some circumstances, but you cannot measure resistance while the PCM is "ON", and with power (ign.) off, the grounding function of the PCM would be disabled.
If worst comes to worst, you could simply disconnect 904 from the PCM, and connect it to a "Hot in Start or Run" 12 V lead, through a 250 ohm resistor, start engine, check voltage on 904. If you find about 8 volts, check voltage at battery. If more than 13, alternator is working. I picked 250 ohms because the old, non-CAN system used a plain old lightbulb with a 500 ohm resistor across the bulb. Purpose was, to still allow alternator to function if bulb burned out. So, 250 ohms is a guess. If that gives you more than 8 V on 904, try a 500. If you succeed in finding the alternator works, then PCM may likely be bad. Ten, your call whether you want to try replacing the PCM, or charge your battery using a jury-rig.

The '04 Manual shows the CHARGE indicator as an actual light bulb, but I am of the thinking you cannot access it. If you could, you could re-connect that bulb with a 500 ohm resistor across it, exactly as I've described above, and thereby still have a functioning, stock-looking IP, just no PCM control over the idiot light. Might not even throw a code, it's doubtful in my mind that each and every current-carrying device is monitored for function. Good luck. imp

 

[Geologist]

My apologies, I should have been more clear.

In the service manual under PC/ED section (Powertrain Control/Emissions Diagnosis Manual)-> Pinout Tests-> HY: Generator/Regulator System section it shows HY4 as follows:

HY4 CHECK EEC CONTROL CIRCUIT IN PCM
⦁ Key off.

⦁ Remove generator and PCM harness connectors.

⦁ Measure resistance between the I-Line and VPWR through the PCM where applicable for Expedition/Navigator.

⦁ Measure resistance between the I-Line and ground through the PCM where applicable for Explorer/Mountaineer.

Are the resistances within the ranges in the table?

Resistance Values for PCM Circuits(Ohms)

VEHICLE TYPE LOW RANGE HIGH RANGE
Expedition/,Navigator 1550 1650
Explorer/,Mountaineer 100 150

If Yes
GO to HY5.

If No
REPLACE PCM (refer to Section 2), Flash Electrically Erasable Programmable Read Only Memory (EEPROM) .

Hope that helps. In the meantime I will work on replacing the pink\blk wire under dash and give your suggestion a try.

Thanks again.

 

[Bluedog1193]

My apologies, I should have been more clear.

In the service manual under PC/ED section (Powertrain Control/Emissions Diagnosis Manual)-> Pinout Tests-> HY: Generator/Regulator System section it shows HY4 as follows:

HY4 CHECK EEC CONTROL CIRCUIT IN PCM
⦁ Key off.

⦁ Remove generator and PCM harness connectors.

⦁ Measure resistance between the I-Line and VPWR through the PCM where applicable for Expedition/Navigator.

⦁ Measure resistance between the I-Line and ground through the PCM where applicable for Explorer/Mountaineer.

Are the resistances within the ranges in the table?

Resistance Values for PCM Circuits(Ohms)

VEHICLE TYPE LOW RANGE HIGH RANGE
Expedition/,Navigator 1550 1650
Explorer/,Mountaineer 100 150

If Yes
GO to HY5.

If No
REPLACE PCM (refer to Section 2), Flash Electrically Erasable Programmable Read Only Memory (EEPROM) .

Hope that helps. In the meantime I will work on replacing the pink\blk wire under dash and give your suggestion a try.

Thanks again.

I know this is a longshot, but was there ever a solution to the problem?
I'm having the same exact issue.

 

[flsmokeater]

I know this is a longshot, but was there ever a solution to the problem?
I'm having the same exact issue.

I am also having this exact same issue, but with my 2006 4.6 V8 Explorer

 

[greenpinto72]

I have the same issue with my 2004 EB 4.0 v6 Explorer.

 

[AlexCalderon02]

Had this issue and it went away after replacing the PCM. You can confirm it's the PCM by probing the I wire. Or you can just bypass the PCM and have it charge constantly.