Transmission Hot Mode Vortec Black Box???

**ralmo94** · 01-03-2021

98 K2500 Silverado 7.4L 454 4l80E 4x4
Operating System 16263425

I was towing and the truck did not want to hold gears like I had it programmed to, would down shift way too easy.

I was logging, and use HP Tuners. I usually log all transmission related channels that I can.

So when I went to review the log to see why, I seen it went into Hot Shift mode.
Trans Fluid Temp 163°F
Engine Temp 199°F

Seems simple enough, raise the hot temp in the tune.

I went into the tune editor, under Transmission Diagnostics

Trans Overtemp
Set Temp 266.9°F
Clear Temp 264.2°F
P1870 Trans Component Slipping
Diagnostic Enable Temp 301°F
Diagnostic Disable Temp 322°F

I was never anywhere near these temps!?!

Is there something HP Tuners doesn't have defined for this, or whats going on?

I guess now I know why it's shifting the way it is I can copy my normal or cruise Shedule to the Hot Shedule. But I would like to understand why it went to Hot Shift in the first place

I know there is at least one guy on here familiar with the vortec black box's. Any body have any Idea, please let me know.

I'm wondering if whatever it is would follow to a 0411 swap?

Thanks in advance to the most helpful forum I know of.

**B52Bombardier1** · 01-04-2021

Neither your listed engine temperature (199 F) or your transmission temperature (163 F) are hot enough to trigger trouble. I'm thinking there's something else going on here inside your transmission.

How many miles on the transmission? Changing those Abuse Mode temperatures to higher values could simply be rearranging the deck chairs on the Titanic . . . .

Rick

**ralmo94** · 01-04-2021

Originally Posted by B52Bombardier1

Neither your listed engine temperature (199 F) or your transmission temperature (163 F) are hot enough to trigger trouble. I'm thinking there's something else going on here inside your transmission.

How many miles on the transmission? Changing those Abuse Mode temperatures to higher values could simply be rearranging the deck chairs on the Titanic . . . .

Rick

I understand what you mean, but I didnt change the temp thresholds. That's what they were already. I have never seen over 200 on the transmission. Truck had 140,000. Shifts real good and solid. I don't think it's anything mechanical. Fluid is nice red color and does not smell burnt at all. I looked at another log, and it went to hot shift when trans temp was only 153, engine temp was 199.

Is there a chance it has anything to do with the scanner and gauge cluster reading different speeds? They are about 2 mph different at 60.

**ralmo94** · 01-04-2021

Went into hot mode again. Shift schedule was better, as I changed the hot schedules.
I noticed it seemed like the converter clutch didn't seem to want to stay locked in OD.
I pulled it down into 3rd, and it had no problem. Looking at the scanner, trans temp was 176°f. Pulled over checked the dip stick. Not hot but slightly warm to the touch. Did not feel slippery at all. It was dark, but I don't think it was a brilliant red. Maybe closer to a tan color? Hard to say and not sure a picture would represent for well.

The confusing part to me is, what it making it go into hot mode. Trans temp was not hot, engine was not over heated. Is it possible that it couldn't fully lock the converter and that did it?

I'm wondering also if it has the original atf from 1998? Should I drop the pan and change a filter?
Could old fluid cause the tcc to be not as grabby?
Also thinking about a aux cooler, but I never seen over 200° even on steep steep mountain passes, I don't really think that will save anything, but I'm all for keeping it cool.

**ralmo94** · 01-05-2021

I set up a new gauge screen on hpt for reviewing the logs, and discovered something interesting.

In 3rd gear, the output shaft RPM is higher than the Input shaft Rpm?

Doesn't that mean overdrive? So if it is showing overdrive in third, then that would mean something wrong with shaft RPM Sensor.

Also TCC Locked, 100%, and Engine RPM is 582 higher than Input RPM?

Bad TCC?

Also Wiped Fluid on napkin.... not as clean as Originally thought wiping on fingers.

Has the Titanic Hit the Iceberg, and the passengers don't know yet?

**ralmo94** · 01-05-2021

I think I figured the overdrive issue. I guess while trying to dial the speedometer in some how I changed the VSS P./REV - Trans to 41.5273

All Info I have found says this should be 40, but stock setting was 31? either way, 41.5273 I'm sure is wrong.

Is this in the trans, or the T Case?

Thanks

**ralmo94** · 01-05-2021

So I put the vss to 40, and calculated new speedo cal. Will try out tonight.

Also went back to a shift schedule I wrote from scratch.

**ralmo94** · 01-06-2021

So 40 was not correct. apparently this is labeled wrong by hP? 31 is correct, and 31 is Input Shaft count.

After correcting that, it has not went into Hot Shift mode.

Evidently the setting for the gauge cluster is based on the actual vss, and the trans section is based off of a 4.10 gear ratio for vehicle speed calcs.

That explains why I have different speeds in the gauge cluster, and the scanner. It's close now, and cluster reads spot on with GPS at 70MPH, so I am not going to mess with it any further, I can just alter my shift speeds to reflect the difference.

Thought I would update here in case anyone had a similar issue. Hate finding threads that don't conclude when researching issues someone else had.

From what I found, this generation of computer is not explained very well, and some things might be defined differently. If you open a 98 file in HPT, then open a $0D bin in Tuner Pro, you see tons more tables and scalers and stuff in TP, so much so that it can be confusing. So there is a lot left out in these.

I'm sure most of you already know all this, but just thought someone might come across this thread to learn.