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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6212
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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I have a 2005 ford explorer I have a rebuilt gh output

Customer Question

I have a 2005 ford explorer I have a rebuilt high output alternator with also a battery bank of 6 batteries. all batteries sitting at the right voltage. my problem is I go to start the truck and it's just running off the battery the alternator will not kick in. I replaced the voltage regulator in the alternator same issues. then I also checked the 3 fusible link's there is on continutnity on all of them right off the fuse box. I replaced both alternator plugs the voltage regulator plug as well as the plug for the stator the small grey rectangle one. all of the batteries read well. since It has a smaller pulley the belt is the correct size and It does not jump nor slip. Im at the crossroad's of not knowing what in the world it can be and I know electrical pretty well. please help asap I need to get my truck back on the road so I can get back and forth to work.
Submitted: 1 year ago.
Category: Ford
Expert:  A. Penland replied 1 year ago.

Are you sure this is a 2005 Ford Explorer SUV?
Ford did not make an electric Hybrid Explorer in 2005.

Because you state you replaced a bank of 6 Batteries.

Customer: replied 1 year ago.
No my bank of 6 batteries is for car audio. Its not an electric hybrid.
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
Hello are you there??????
Customer: replied 1 year ago.
Live phone or conversation here is fine. Are you still there?
Expert:  A. Penland replied 1 year ago.

Sorry, did not know. The charging system on your 2005 Ford Explorer is controlled by the PCM. It needs to see 14.7 volts at start up or the PCM will set the warning light and cause the alternator not to charge. If you still have it all wired into the factory harness, that could be the issue. The PCM acts as the voltage regulator.

Customer: replied 1 year ago.
Very true is there anyway to check the pcm on this suv. Back probe or some how disconnect etc....an yes its throwing a warning light
Expert:  A. Penland replied 1 year ago.

I can post a pin point test for you to follow if you have a digital multimeter.

Customer: replied 1 year ago.
I do have a multi meter a snap on one. So not cheap barely works one lol. Where is the pcm located in this truck
Expert:  A. Penland replied 1 year ago.

Under the hood on the passenger side firewall. There are three big wiring connectors going to the firewall that are in a row.

Customer: replied 1 year ago.
Which one do i check what exatcly wouldbi set multi meter to to check for what at the plug
Expert:  A. Penland replied 1 year ago.

It will be the center connector. Below is a pin point of the wiring in the connector.

The settings will either be DC volts or OHMS, depending on what the step in the test directs you to.

Customer: replied 1 year ago.
which pin/pins would i check an what should it read
Expert:  A. Penland replied 1 year ago.

The pin point test will tell you what pins in the connector to test. I will also show you pictures of the connectors and list off the pin # ***** the wire color.

Example, (LG/RD)= Light Green/Red striped.

Customer: replied 1 year ago.
Ok but which one do i check an what ohms does it have to be inbetween an car off batt disconnected also
Expert:  A. Penland replied 1 year ago.

Have you read over the pin point test I posted for you?
It will tell you the specs you are testing from, ask you a yes or no question which will lead you to another step.

Each step explains what you are checking for, the wiring colors and the connectors. Also the results either OHMS or VOLTS.

Customer: replied 1 year ago.
U understand that but can you tell me what ohms that wire has to be of the connector off the pcm
Expert:  A. Penland replied 1 year ago.
  • Ignition OFF.
  • Disconnect: PCM C175b.
  • Measure the resistance between the PCM C175B-24, I circuit 904 (LG/RD), harness side and the generator C102A-1, I circuit 904 (LG/RD), harness side; and between the PCM C175B-24, I circuit 904 (LG/RD), harness side and ground.

Is the resistance less than 5 ohms between the PCM and the generator, and greater than 10,000 ohms between the PCM and ground?

Customer: replied 1 year ago.
just ground the multi meter neg side to batt is that ok. An pisitive leave to check harness plug which you said is center plug pin 904 correct? Also have batt disconnected as well?
Expert:  A. Penland replied 1 year ago.

It is the Light Green/Red striped wire which is the first pin in the alternator three wire connector and pin #24 in the PCM connector on the firewall. With the battery disconnected completely, set the meter to read OHMS and place one meter lead on the alternator connector (unplugged from the alternator) the light green/red striped wire and pin #24 in the center PCM connector (unplugged from the PCM).

Customer: replied 1 year ago.
If comes up bad what does that mean? Also is there this huge 175 amp maxi fuse everyone talking about in a 2005 explorer or is it only older ones
Expert:  A. Penland replied 1 year ago.

Ok. Since you have not read the pin point test, set the meter to DC VOLTS. Reconnect everything back together. Then place the black probe on the negative battery post and the red lead on the 13mm nut on the alternator where the BLACK/ORANGE striped wire connects. You should get 12 volts there with the key off.

Customer: replied 1 year ago.
I have that.
Expert:  A. Penland replied 1 year ago.

Ok. Unplug the alternator three wire connector and check the voltage at the ORANGE/LIGHT BLUE wire the same way. What volts do you get.

Customer: replied 1 year ago.
12.82 car off key turned forward voltage regulator plug unplugged from alt
Expert:  A. Penland replied 1 year ago.

Ok. Start the engine and check the voltage at the alternator connector at the LIGHT GREEN/RED striped wire. Let me know the voltage on that wire.

Customer: replied 1 year ago.
With connector plugged into alt or not plugged in
Expert:  A. Penland replied 1 year ago.

Unplugged and then plugged in. Both with the engine running.

Customer: replied 1 year ago.
Engine running 12.57v not plugged in
Customer: replied 1 year ago.
Plugged in engine running 0.87v
Expert:  A. Penland replied 1 year ago.

Ok. Plug everything back in. The set the meter to volts and place the red lead on the battery positive post and the black lead on the alternator post with the 13mm nut. Then start the engine and see what the voltage reading is. This is a voltage drop test.

Then place the red lead on the alternator post and the black lead on the negative battery post and start the engine. See what the voltage reading is.

Customer: replied 1 year ago.
Ok so positive multi meter lead on battery negative on red alt post .0.02v then black lead on negative battery red on alt post it reads 12.48v
Expert:  A. Penland replied 1 year ago.

Ok. DO you have the V6 or the V8 engine?

Customer: replied 1 year ago.
V6 4.0 sohc
Expert:  A. Penland replied 1 year ago.

The problem is in the alternator.

Expert:  A. Penland replied 1 year ago.

I just walked you through the complete pin point test.

Customer: replied 1 year ago.
Its brand new alternator though fully rebuilt 250amp
Customer: replied 1 year ago.
Anything else???? Does this off explorer have the175 amp maxi fuse
Expert:  A. Penland replied 1 year ago.

Since you have power at the alternator post, the fusible link is good.

Customer: replied 1 year ago.
Thats what i thought if i check the pin in center connector at pcm an does notbread the right ohms what does that mean
Expert:  A. Penland replied 1 year ago.

We've checked that wire earlier and you are getting voltage on that wire, the LIGHT GREEN/RED striped wire with the engine running and the alternator unplugged.

That wire is good.

Customer: replied 1 year ago.
Ugh......idk where to go im lost. The alt fully rebuilt 250amp wiring is good new plugs wiring all checks out good what is left what is causing this???????
Expert:  A. Penland replied 1 year ago.

Have the alternator tested off the vehicle and see what the amperage and voltage that it puts out.

Customer: replied 1 year ago.
If that turns up good then what
Expert:  A. Penland replied 1 year ago.

It may not be able to handle the 6 battery load.

Customer: replied 1 year ago.
There not even hooked up when checking all this an i was wrong there 4 extras not 6.
Expert:  A. Penland replied 1 year ago.

So you were only running on the main engine battery under the hood?

Customer: replied 1 year ago.
Yup
Expert:  A. Penland replied 1 year ago.

One last test and this is not in the pin point test. Start the engine and check the voltage at the battery and then at the alternator post.

Customer: replied 1 year ago.
Checked that both reading same. Im gonna pull alt go have it bench tested
Expert:  A. Penland replied 1 year ago.

As long as it is over the battery voltage reading when the engine is off tells me it is the alternator.

Expert:  A. Penland replied 1 year ago.

Please let me know if you need any more help.

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