4L80E, Alternator, Van Issues (long post)(please help)

[ThePIGSmith]

I bought my 1993 GMC 3500 series van for cheap, because it needed a transmission.

Recently, through a friend/adult leader at Scouts, I was able to pick up a 4L80E from a small private salvage yard.
This unit had been previously remanufactured by GM and had a sticker on the bell to this fact.
I took to it to a local Transmission Shop her in Fort Wayne.
This same friend knew the owner of this shop and was able to get my 4L80E installed.
The owner (and most all other shops in town) would typically not install salvage yard units.

Anyways, the shop took this 4L80E, and with a new Diesel torque converter and filter/fluid change installed this in my van.

Should have been an easy and quick process…no big deal…WRONG!
The 4L80E was newer than ’93 and had a different connector than that van wiring harness.

So, the shop modified my van’s wiring harness so it would plug into this newer 4L80E
During that test drive, it would not shift out of second gear.
The shop determined via a diagnostic tool that a couple of solenoids in the valve body needed to be replaced.

After these were replaced, it still would not shift out of second.
As the diagnostic tools reported the tranny was healthy, the only things left were the wiring on the van or the computer.

This van has worked on a horse farm and there was rat poo everywhere (no, not mouse, but rat, as their poo looked like rabbit pellets)
Apparently, the wiring was next issue to be fixed.
I am not for sure if rats had chewed the wiring harness or the wires were old, brittle and chaffed or the modifications the shop made were not correct.

After these repairs were made, the diagnostic tools indicated the computer was bad.
The shop sent the TCM to California for repair.
The CA shop sent the TCM back and said there was nothing wrong with it.
Not convinced, my local shop ordered a new TCM from GM.
This worked.

The shop called to let me know it was finished, but to bring a battery that the battery (yes a single battery)
was weak and the alternator was not putting out much or if any.

I came switched batteries with a spare one that I had and brought the van home.
By the time I got home, the battery was dead.
I put the original battery back in, as it was a larger unit and charged it for a few days.

This past weekend, I went to use the van, it started, but it battery power dropped off quickly.
It was apparent that my alternator was discharging my battery, leaving me with no power for lights or anything.
The troubling issue is the tranny would not shift out of second.
I contributed this to zero power to operate the TCM.

So, my plans are to replace the alternator and the battery.

I do trust this shop and their work.
This shop spend hours and hours (about six weeks) working on this van.
The original quote/bill was for:
$150 for the R&R
$150 for a new Torque Converter
$100 for the wiring harness parts/modifications/shop supplies
Then after the weeks of troubleshooting, he only charged me $150 the new TCM and his time.

I am seeking comments, opinions and some reassuring
Did driving the van with the lack of power hurt anything?
What are the chances of R&R the alternator/battery and all will be good?
I hope the wiring to the alternator/battery is in good shape (not rat chewed)
Is there a special panel on the passenger side dog house to gain access to the alternator?

The good in all this…that 6.2 ran great!

[EWC]

Should be a second battery on the driver side under the van behind the seat . Took some parts from a 95 and that was where I found it . I'd test both batteries to start .

[Robyn]

Be careful to check all the cables for connection.
These side terminal critters are well known to corode badly under the jackets and they degrade to a point that they will not work.

Low voltage will drive the ECM nuts and make life a Real Bitch.

Be sure the ground cables are good too. These can and do go south at the block.
Even new cables are sorely lacking in quality.

Get the alternator checked and be sure the wire that connects it to the battery is good and has good connection.

Now you also need to be sure the feed from the battery to the junction box (main power feed to the truck) is good.

When things are good you should have 14+ volts at the battery + and also at the main feed to the truck with it running. Sometimes they will drop to 13.7 but this will suffice..

Good luck

Robyn

[ThePIGSmith]

Thanx.

I hooked my battery charger on Thursday evening and checked it before Church services this morning.
Sure enough, I do have a second battery enclosed in a steel box on the driver's frame rail.

I put the key in, waited for the Glow Plug light to go off and it turned over and started.
The voltage gauge needle was just a little below the center of the gauge, maybe 12 volts if the center is 14 volts.
I did not have much time, so I did not take off the battery charger to see if the alternator would charge the batteries or if the batteries would hold a charge on their own.
This is my next task.

A dual battery/alternator purchase is gonna kill my budget.

I did replace the old battery bolts with standard style from the Autozone.
After reading some here, I may replace these off the shelf items for some standard 3/8 bolts and nuts to make a tighter connection.
I will investigate the battery cables.

[a5150nut]

Use stainless bolts with a jamb nut.

Most parts store can test your alternator. Not bad to have one checked before spending the $$. Also be sure the pulley size matches. If not have it changed there before you take it home.

Your tack drive is the alternator and the wrong pulley will give a bad reading.