Voltage & Transmission issue

[bsamoul]

Hey guys, glad to see so many of you from tahoeforum

Anyways, I was driving today, and earlier I noticed that my voltage was down to the upper part of the orange box where it says 9. Later in the afternoon I was driving home and it was like halfway in the orange box. I went to do a lane change, and put the blinkers on and the radio cut out and so did the blinker. So I pull off and go the other way home off the beaten path because the last thing I wanted was for the thing to stall in the middle of my city's busiest road. As I'm driving down my street, all of a sudden something clicks and the voltage goes back up to the white big line before 14 and the radio clicks back on. I get home and test my voltage and both of my batteries were reading about 12.5 volts. Weird..

As for the transmission: while all this was happening, it was shifting really hard, does anyone have an idea as to why?

What do you think I should do?

[clean454]

output amperage check! check the alternater and also load check the battery and check connections! start there!

[bsamoul]

output amperage check! check the alternater and also load check the battery and check connections! start there!

Isn't the output amperage check what I did by seeing what was going into the batteries?

[JKmotorsports]

Check all your connections from the battery to the alternator, battery to ground, and battery+ to starter and to main fuse box. Also make sure all your ground point are good, including the strap from the body to the motor.
Your tranny issue just may have been from the low voltage. The 4l60e uses electric shift solenoids. Improper voltage to the solenoids can cause erratic operation.

[JDWX]

Yeah, along with what was already mentioned, if the trans gets low voltage, the EPC (Electronic Pressure control solonoid) will cause it to shift hard, as it alters by getting whatever voltage the TCU determines appropriate. Low voltage to EPC = hard shifts High voltage = softer shifts. That design helps to indicate a problem more vividly to the operator etc.

Look for ground issues etc, or a failing alt.

YAY, first post!!

Thanks for bringing me over!

[loulblades]

If I recall correctly from the other forum you put in a solenoid isolator between your batteries. Was the click your isolator? If it was the isolator opening from some reason, your second battery wasn't getting a charge.

On mine if the isolator wasn't getting enough voltage from the alternator for some reason (bad alternator, bad connection, overload, etc), the isolator would open.

Just speculating because I am not sure of your setup.

[bsamoul]

I checked all connections, and they appear to be sound. No problems since then. One other question, do you think I would benefit from a higher output alternator? I'm just wondering if that would be able to handle my electrical needs better especially with two batteries. As far as I know, it's the original one, but it could have been replaced.