SOLVED - 2014 Suburban Electrical gremlins

mikez71 said:

You are talking about the alternator plug, not the rvc sensor right?

Because, I thought it was odd that the bacon612's alt defaulted to 13.6V..
which is the stock initialization duty cycle of 58%=13.6V
But I thought the alternator needed that signal really..

Click to expand...

the 2 pin connector on alternator has to be connected or it does not nothing but spin, at that point you are running off of battery power alone.
no IF's Or's about it. (a 2 pin alternator is activated via pcm signal)
the RVC sensor can be disconnected, this puts the charging system in Default.
it clearly states this is in the factory service manual.
if you have the rvc disconnected and the voltage is dropping under 12v at the battery post's then the alternator is not working, MAYBE a really bad battery but if the battery was eating that much voltage then there would be a short and it would get hot, wires would be warm or something sucking down that many ohms basically a really bad ground be it internal/external

Yea, that's what I thought too, but according to bacon, his acted differently somehow..
solli5packs acted like I would have expected.

Doubeleive said:

Might want to post on your original thread in order to prevent confusion here.......

Click to expand...

Updated and linked to this fourm.

solli5pack said:

Updated and linked to this fourm.

Click to expand...

ya, but best to stick to your post as 2 people posting various things on here is going be confusing I already had to go back and re-read this one because..... crossposting

Doubeleive said:

the 2 pin connector on alternator has to be connected or it does not nothing but spin, at that point you are running off of battery power alone.
no IF's Or's about it. (a 2 pin alternator is activated via pcm signal)

Click to expand...

I have been running for 5 days and about 100 miles with neither the negative clamp sensor or the 2 pin on the alternator plugged in. My voltage is locked at 13.7-13.8 at all times. It's read by a USB c adapter that I have wired into one of the 2 ,12v cigarette accessory leads and has an LCD readout with voltage. It's accurate too as I've compared what it reads against my Klein tools multimeter in my testing. For conversations sake, these values are also the same compared to what my Kenwood headunit reads off of the odb2 port it's connected to.

It's possible that there may be a difference between some of these gmt900 trucks? Mine is a late model 2014.

bacon612 said:

I have been running for 5 days and about 100 miles with neither the negative clamp sensor or the 2 pin on the alternator plugged in. My voltage is locked at 13.7-13.8 at all times. It's read by a USB c adapter that I have wired into one of the 2 ,12v cigarette accessory leads and has an LCD readout with voltage. It's accurate too as I've compared what it reads against my Klein tools multimeter in my testing. For conversations sake, these values are also the same compared to what my Kenwood headunit reads off of the odb2 port it's connected to.

It's possible that there may be a difference between some of these gmt900 trucks? Mine is a late model 2014.

Click to expand...

no, all 2 pin alternators use a pcm signal to activate, be it a 2005 or 2025, so you have been running on battery power, turn on the headlights you will kill it fairly quickly.
when that 2 pin is disconnected you will also have a "service charging system" message in the dic

It couldn't be battery power alone, why would the voltage be 13.6-7? When I first disconnected the two, I hammered the electrical system to see if the voltage output would drop. 4 heated seats, rear defroster, fan on high... Only a minor drop for a moment and then the alternator would return to that steady voltage.

Like I said, I've also driven about 100 miles or so. Id have killed the battery if it was just battery and no alternator power. Or am I not understanding what you are saying?

I do have a service charging system message as well as the red battery light on the speedometer.

Doubeleive said:

the 2 pin connector on alternator has to be connected or it does not nothing but spin, at that point you are running off of battery power alone.
no IF's Or's about it. (a 2 pin alternator is activated via pcm signal)
the RVC sensor can be disconnected, this puts the charging system in Default.
it clearly states this is in the factory service manual.
if you have the rvc disconnected and the voltage is dropping under 12v at the battery post's then the alternator is not working, MAYBE a really bad battery but if the battery was eating that much voltage then there would be a short and it would get hot, wires would be warm or something sucking down that many ohms basically a really bad ground be it internal/external

Click to expand...

bacon612 said:

It couldn't be battery power alone, why would the voltage be 13.6-7? When I first disconnected the two, I hammered the electrical system to see if the voltage output would drop. 4 heated seats, rear defroster, fan on high... Only a minor drop for a moment and then the alternator would return to that steady voltage.

Like I said, I've also driven about 100 miles or so. Id have killed the battery if it was just battery and no alternator power. Or am I not understanding what you are saying?

I do have a service charging system message as well as the red battery light on the speedometer.

Click to expand...

I only disconnected the 2 pin connector on the alternator. Maybe disconnecting both is the trick.....

On a hunch, I ordered a remanufactured Bosch 2 pin 160 Amp alternator from summit racing. After installation I went for a test drive. Problem solved. To recap, I ordered an OEM replacement Delco from them to see if my original alternator was faulty and it didn't fix my problem. I then exchanged it for another OEM Delco from summit. It has a cracked connector for the 2 pin plug but I installed it anyway.

Same voltage issue.

I called summit and told them that the plastic connector arrived cracked so they sent me another OEM Delco.

Same voltage issue.

When today's Bosch reman arrived and solved my problem, I couldn't believe it but here we are.

Let it be known that even new Delco alternators 'made in the usa' can be bad and not tested properly.

I'm just glad I finally found my problem.

So you are saying your voltage now fluctuates?
Is that with the current sensor plugged in or not? (It fluctuates without it plugged in as well, but I am curious)