Found a local Alternator shop that can test the alt up to its max capacity of 136 amps so I will see tomorrow or Wed. Did find a corroded terminal in one of the connector's and cleaned it up, but suspect it is not the issue. Anyway will report back with the find or loss.

 

Now you're on the right path! Good man. Ok, now, I've got a question: WHICH TERMINAL was corroded?

CM

 

I'm sorry, the terminal in one of the connectors down on the drivers side by the fender well, black connector 16 gauge blue with white tracer and honestly might be violet with white tracer. Cleaned it up and put connector back together. Alternator tested good at 136 and the guy said the brushes are a little worn but the alternator is not the problem. He said it maybe the voltage regulator in the ECM which I have a good electrical shop here that I am going to take it to if all the other avenues fail. Got new negative cable put in and am waiting on the coolant sensor to be in tomorrow so I can button it back up.

 

If you are running gas, you won't have an ECM. You will have a PCM and, that was one of the items I listed as to what was a potential root cause: voltage regulator inside the PCM.

Now, UNLESS someone is familiar with electronics and is ESD aware, I would not let just anyone even open the box for, this is a triple microprocessor setup along with other components that are ESD sensitive. If someone is not wearing a ground strap when working on it, they may inadvertently FRY these chips thus rendering the entire unit SCRAP.

I would verify that they KNOW about ESD. Ask them what ESD is. If they don't know or tell you extra sensory dumb-founded- you know you don't want them working on it. ESD stands for Electro Static Discharge. So, hopefully, they will understand this and - ask them if they have certified ESD safe workbenches. If they've got **** carpet benches (don't laugh, I've seen this often) you know you are at the wrong shop.

I would not open the unit yourself either unless you are grounded through at a MIN of 1M OHM and, the unit is placed on a wooden surface.

CM

 

Yes you are right PCM, Power Control Module. Anyway the truck is back together and with it running without any accessories on the voltage at the battery is 13.85 volts. With the brakes applied and A/C on with lights on it drops down to 13.58 in drive and you can hear the fuel pump change rpm, not much but you can hear it. You think this is enough of an issue to worry about it? I could of got a bum PCM from the place I got the rebuilt unit. I guess I could always take it back and tell them the dealer says that the voltage regultor has a problem? Just curious but what does your truck run at voltage wise in idle with the brakes on? I don't know if not even half a volt is a big deal. But I would think so on these computer operated vehicles.

 

Now we have some results. This is what I was waiting for- good. Now, that measurement difference is a, non-issue. That's only slightly over a quarter of a volt at .27 volts delta.

Now, <IF> the regulator were going out, you would be reading a much larger delta than .27 volts and, remembering this, for the regulator, there's a tolerance. Now, exactly what this tolerance is: is unknown here. One thing I do not have access to is the PCM specifications and drawings (yet). But, one thing you may want to test is under high load conditions.

Do this:

Place meter in window to where it is facing you. Measuring across the battery, with the vehicle running- turn on the following CKTs one at a time and wait 10 seconds between cycling on the next CKT.

-Turn headlamps <ON> Note voltage reading wait ten seconds. Verify voltage comes back up to ~ 13.XX -14 VDC. Does voltage jump up / down or, cut out?

-turn heater motor <ON> and to HI. Note reading and, note same as above.

-depress brake and note voltage reading while holding brake for five seconds. Same as above- note results voltage wise

That will give you some indication as to what is going on with the voltage regulator output. It's a cheap and dirty test but, it's better than nothing.

Now, the question here is: what is the voltage doing at the FUEL PUMP. That's one thing we ought to take a look at and, here's how.

NEXT TEST: FUEL PUMP ELECTRICAL VOLTAGE VERIFICATION TEST

-With the vehicle <OFF>, BACKPROBE the E-connector AT THE FUEL PUMP. NOTE: Depending on WHICH FUEL PUMP you have, it's either going to be one of TWO types of E-connectors- a FOUR PIN or, an EIGHT PIN connector.

FUEL PUMP ELECTRICAL TEST: FOUR WIRE CONNECTOR

1. Using paper clips, wrap one paper clip around the NEG probe of the meter. Do the same for the POS (+) probe as well.

2. Using electrical tape, please mask off the NEG terminal minus 1/2 inch to prevent accidental shorting. This means, WRAP tape around the paper clip leaving 1/2 inch BARE. NEXT.

3. Carefully INSERT the POS (+) probe into the RED 12AWG wire hole. NOTE: DO NOT REMOVE THE E-CONNECTOR from the FUEL PUMP - it is to remain connected at all times during these tests.

4. Carefully insert the NEG (-) probe into the BLK 12AWG wire hole at the E-connector.

NOTE: PAY ATTENTION TO MAKING CONTACT WITH THE PINS BY FEEL. PAY ATTENTION TO POTENTIAL TO SHORT. IF PAPER-CLIPS ARE CLOSE TO TOUCHING EACH OTHER- STOP AND REWIRE TO ENSURE NO SHORT WILL OCCUR.

5. TURN KEY <ON> and record voltage to pump under NO LOAD condition.

6. TURN KEY <START> and record voltage to pump under idle condition.

7. DEPRESS brake and record voltage to pump under braking condition.

8. TURN KEY <OFF>

END OF TEST.

Remove DMM and post back the results.

EIGHT PIN CONNECTOR METHOD:

Same as above with the exception of the pin-out at the rear of the E-connector. For this connector, the two wires needed are on opposite sides, diagonally with, the HOT being in the lower RIGHT corner and, the NEG in the upper LEFT corner. (Note: this is from memory: it's either that way or just the opposite- I cannot remember exactly where the HOT is located- FYI

NOTE: The wire color MAY or MAY NOT be RED and BLK however, the AWG of those two wires will be the same and, the only TWO of 12AWG so, it will be obvious as to which two they are.

CM

 

I will try to back probe the connector at the pump over the weekend and the other stuff and let you know hopefully Sunday. Thanks again.