Q: SHIFT UP

[Paul Workman]

(...or is that "UP SHIFT")

Is the light triggered simply at a fixed rpm, or dependant on variable demand conditions?

TIA,

P.

[GOLDCYLON]

Originally Posted by Paul Workman

(...or is that "UP SHIFT")

Is the light triggered simply at a fixed rpm, or dependant on variable demand conditions?

TIA,

P.

Paul the short answer is Yes. The longer answer is listed below with all the factors for CAGS or Skip Shift from GM

Gear Select - Skip Shift (CAGS)
To ensure good fuel economy and compliance with federal economy standards, SECOND and THIRD gear are inhibited when shifting out of FIRST gear, under the following conditions:

Coolant temperature is above 50°C (122°F)
Corvette speed is 20 - 29 km/h (12 - 19 mph)
Throttle is opened 35 percent or less

Skip Shift Description and Operation
The skip shift solenoid is a Peformance feature which forces the driver to shift from first gear to fourth gear during light acceleration and low engine load conditions. This feature is used to ensure good fuel economy and compliance with federal economy standards. The skip shift system consist of the following components:

· The powertrain control module (PCM) .
· The skip shift solenoid.

· The skip shift lamp. With the ignition ON, battery voltage is supplied directly to the skip shift solenoid. The powertrain control module (PCM) controls the solenoid by grounding the control circuit. When the skip shift system is active the PCM also grounds the control circuit of the skip shift lamp. The lamp illuminates to inform the driver that the 1-4 skip shift is engaged. The PCM determines when the skip shift system is active when the following parameters are met:

· The vehicle speed is between 24 - 31 km/h (15 - 19 mph) .

· The engine coolant temperature (ECT) is greater than 77°C (171°F) .

· The BARO is greater than 76 kPa.

· The accelerator pedal position (APP) is less than 26 percent. When the conditions are met the powertrain control module (PCM) grounds the skip shift solenoid control circuit. This energizes the skip shift solenoid and mechanically blocks the gear shift lever from going into the second or third gear positions. When the drivers pulls back on the shift lever with the system enabled the transmission will go into fourth gear.

When the conditions for skip shift engagement are no longer met the powertrain control module (PCM) disables the skip shift solenoid, allowing the driver to use second and third gears.
Once the skip shift solenoid is enabled the system will not be re-enabled until the vehicle speed returns to 0 km/h (0 mph) and the conditions for enabling skip shift solenoid are met.


GC

[A1990]

When I had stock gears in my car, I would sometimes cruise in 5th to prevent the drone of my B&B's. After a period of time my "shift up" light would come on.

Disabled in the chip now.

[Paul Workman]

GC,

Oh, my fault for not being clearer: Not to be confused with the CAGS 1 to 4 shift light, I was referring to the other shift (shift up) light, actually.

P.

[GOLDCYLON]

Originally Posted by Paul Workman

GC,

Oh, my fault for not being clearer: Not to be confused with the CAGS 1 to 4 shift light, I was referring to the other shift (shift up) light, actually.

P.

Yep understood I know exactly what you mean. With that being said I wonder if its an RPM or parameters issue like CAGS?

[gbrtng]

I think it's just time based - you have to run at a fixed (almost) speed for
about a minute. Change the throttle position and it goes out for a while.
It's kinda useless but at least it's in an area where you hardly notice it.
My guess is some software designer had room for a few more lines of code and was bored with life ...

[tpepmeie]

The E-Light (for Economy), or shift light, is primarily a function of throttle position and RPM. There is a delay feature which sets the time at TPS to enable the light. The lamp can be activated once Coolant Temp, speed, MAP, TPS, and RPM thresholds are met. There is a forced activation at a certain RPM as well. That is what is mostly adjusted for different "Shift Light" rpm preferences in custom calibrations.

So, yes, it may seem a bit random as to when it lights up, given the various criteria involved.

By the way, this function is disabled (but still present) in the later release service calibrations. And removed altogether in some 93-95 calibrations.

Todd

[tf95ZR1]

Originally Posted by tpepmeie

And removed altogether in some 93-95 calibrations.
Todd

Thanks, Todd
My 95 does not have this "feature" and I have heard talk about it.
Now I know.........
My "shift up" light is in my head and caused a poor run in the mile shoot-out
in Las Vegas. The way the engine was screaming I thought I should shift
into 6th. Big mistake- slowest end speed. Next runs, let her scream!
Whoopee!!!

PS Hey Ron, don't you have another Nellis Mile Run in April?

[Aurora40]

Mine only comes on at ~6,500 RPM. Marc had to re-enable it though, it's off in the base program. I believe it's bit-limited to like 6,500 or somewhere thereabouts. It's not that useful a light, but nice to have it come on since it's there anyway.

[tpepmeie]

Originally Posted by Aurora40

Mine only comes on at ~6,500 RPM. Marc had to re-enable it though, it's off in the base program. I believe it's bit-limited to like 6,500 or somewhere thereabouts. It's not that useful a light, but nice to have it come on since it's there anyway.

As is, it is limited to 6375 (255 x 25). But it can easily be modified to go higher, with a change to a few bytes in the program code.