6.5 non turbo diesel 4L80E chevy p30 StepVan

[ak diesel driver]

Most likely a new alternator

 

[WarWagon]

You are our eyes and ears to see what is going on so we can help. Thanks for the info. The input speeds look ok so engine RPM and trans speed sensors are working. As an aside IMO it's a little off but NOT the trans problem: What is the engine RPM supposed to be? Should be on the emissions sticker both cold with cold advance and high idle on and hot idle.

Was the engine running with the voltage @ak diesel driver noted?

Batteries should be at 12.6V minimum. Disconnect and load test them. Remove the ground post cables first on both battries then mess with the positive cables. (Short the ground cable to the fender nothing happens. With BOTH negative cables off your tool slips on the positive post and hits the fender nothing happens.) One battery may have a shorted cell and be dragging the system voltage down. A reading of ~10V means the battery is bad: Just Replace IT! Batteries with shorted calls can be dangerous if you try and revive them. Further they need to be replaced in pairs. (Assumption this is a dual battery system.)

Engine running should be around 13.5V. Measure the output stud of the alternator before saying it's bad. There is a fusible link off the charge wire that blows if the diodes short for example: keeps things from burning down. If it doesn't get a start voltage the Alternator will not "turn on". Bad wire, bad connector, burned out indicator lamp, etc.

 

[Brenttt]

You are our eyes and ears to see what is going on so we can help. Thanks for the info. The input speeds look ok so engine RPM and trans speed sensors are working. As an aside IMO it's a little off but NOT the trans problem: What is the engine RPM supposed to be? Should be on the emissions sticker both cold with cold advance and high idle on and hot idle.

Was the engine running with the voltage @ak diesel driver noted?

Batteries should be at 12.6V minimum. Disconnect and load test them. Remove the ground post cables first on both battries then mess with the positive cables. (Short the ground cable to the fender nothing happens. With BOTH negative cables off your tool slips on the positive post and hits the fender nothing happens.) One battery may have a shorted cell and be dragging the system voltage down. A reading of ~10V means the battery is bad: Just Replace IT! Batteries with shorted calls can be dangerous if you try and revive them. Further they need to be replaced in pairs. (Assumption this is a dual battery system.)

Engine running should be around 13.5V. Measure the output stud of the alternator before saying it's bad. There is a fusible link off the charge wire that blows if the diodes short for example: keeps things from burning down. If it doesn't get a start voltage the Alternator will not "turn on". Bad wire, bad connector, burned out indicator lamp, etc.

The engine was running with that voltage

 

[MrMarty51]

The engine was running with that voltage

Be absolutely sure that the replacement alternator has the front pulley for the diesel engine.
Gas engine pulleys is smaller and if the van has a tachometer, it will throw off the tach reading.
Most over the counter alternators will fit the hole, but, the pulleys will be for a gasser.
I do not remember the diameter of the diesel pulley, maybe someone in the forum can post in that information.
I too need to find out, pulley on My alternator is for a gasser.

 

[Brenttt]

You are our eyes and ears to see what is going on so we can help. Thanks for the info. The input speeds look ok so engine RPM and trans speed sensors are working. As an aside IMO it's a little off but NOT the trans problem: What is the engine RPM supposed to be? Should be on the emissions sticker both cold with cold advance and high idle on and hot idle.

Was the engine running with the voltage @ak diesel driver noted?

Batteries should be at 12.6V minimum. Disconnect and load test them. Remove the ground post cables first on both battries then mess with the positive cables. (Short the ground cable to the fender nothing happens. With BOTH negative cables off your tool slips on the positive post and hits the fender nothing happens.) One battery may have a shorted cell and be dragging the system voltage down. A reading of ~10V means the battery is bad: Just Replace IT! Batteries with shorted calls can be dangerous if you try and revive them. Further they need to be replaced in pairs. (Assumption this is a dual battery system.)

Engine running should be around 13.5V. Measure the output stud of the alternator before saying it's bad. There is a fusible link off the charge wire that blows if the diodes short for example: keeps things from burning down. If it doesn't get a start voltage the Alternator will not "turn on". Bad wire, bad connector, burned out indicator lamp, etc.

I don’t think the emissions sticker is there anymore to confirm the engine RPM specs .
Here is the build info

 

[Brenttt]

I don’t think the emissions sticker is there anymore to confirm the engine RPM specs .
Here is the build info

I messed around with the truck today it seems the truck shifts upto 3 gear but does not shift beyond that. I had the tech 2 hooked up and shifted through the unit with now problems through all the gears just won’t do by itself

 

[WarWagon]

Did you measure the voltage and confirm with a meter what it really is?

Aside of that something mechanical in the transmission needs to be "fixed". This is the code "85" commanding 4th and it's still in 3rd.

 

[Brenttt]

The truck has no codes at all now voltage is 13 volts. Batteries needed charged Won’t go past 3rd grear on its own using the tech 2 shifted through all the gear no problem

 

[MrMarty51]

The truck has no codes at all now voltage is 13 volts. Batteries needed charged Won’t go past 3rd grear on its own using the tech 2 shifted through all the gear no problem

I am no professional transmission man, but, to Me, it seems that if the trans can be commanded to shift into the higher gears through an wxternal source, like the tech2, then the problem is somehow related to the command module, or, the wiring between the solenoids and the command module.
Being that it seems to shift just fine through the external source tells Me that the mechanicals of the transmission is just fine.

 

[Brenttt]

I am no professional transmission man, but, to Me, it seems that if the trans can be commanded to shift into the higher gears through an wxternal source, like the tech2, then the problem is somehow related to the command module, or, the wiring between the solenoids and the command module.
Being that it seems to shift just fine through the external source tells Me that the mechanicals of the transmission is just fine.

Yes I would have to agree with you I wonder if anyone else here would maybe know some more

 

[MrMarty51]

From the power train control module, to the transmission, disconnect the harness from that and from the transmission, test for continuity between the two terminal ends on every wire that is between the two.
Check to be sure that all them little connectors are in place and have not been pushed back within their plugs.
I also recommend getting some root canal files, YUP, dental tools, use those to file and scrub them tiny connectors. Them files is the only thing I have found that can get inside of those connectors. I trim off the very fine ends of them, just to prevent one from breaking off and getting lodged within the terminal.

 

[MrMarty51]

https://www.amazon.com/dp/B07Q8W64XS/ref=tsm_1_tp_tc

 

[WarWagon]

Is it saying "Gear Commanded" 4th on the Tech 2?

The rev out without shifting may be something we are missing and it's in limp mode still.

As you have other gears the "electric" is all working. Something is "broken" in the trans where it won't mechanically shift to 4th. My first 4L80E in the 1993 went "BOOM!" Crunch Crunch Crunch when it "lost" OD/4th. Took a rebuild and some hard parts to fix it.

You have 4th selected not 3rd as a misadjusted linkage could do this. "N" would be OD/4th then.

 

[Brenttt]

Is it saying "Gear Commanded" 4th on the Tech 2?

The rev out without shifting may be something we are missing and it's in limp mode still.

As you have other gears the "electric" is all working. Something is "broken" in the trans where it won't mechanically shift to 4th. My first 4L80E in the 1993 went "BOOM!" Crunch Crunch Crunch when it "lost" OD/4th. Took a rebuild and some hard parts to fix it.

You have 4th selected not 3rd as a misadjusted linkage could do this. "N" would be OD/4th then.

It shift into 4th with the tech 2 when I take it on a test drive I watch it shit up to 3 gear then I shift up with the tech 2 it going up a gear for sure cause the engine is not reving high and I’m doing 50mph in a step van

 

[Brenttt]

It shift into 4th with the tech 2 when I take it on a test drive I watch it shit up to 3 gear then I shift up with the tech 2 it going up a gear for sure cause the engine is not reving high and I’m doing 50mph in a step van

 

[WarWagon]

So you force it to shift to 4th with the Tech 2? Or does it shift to 4th with it plugged in?

Does the TCC ever lock up?

 

[Brenttt]

I read

So you force it to shift to 4th with the Tech 2? Or does it shift to 4th with it plugged in?

Does the TCC ever lock up?

i you the shift up button on the tech 2 there is no lockup