Transmission Control Module Scan Tool Information (2ML70)

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The Transmission Control Module Scan Tool Data List contains all transmission related parameters that are available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists, and in some cases may appear more than once, or in more than one data list in order to group certain related parameters together.

The values below represent a typical display recorded from a properly functioning system.

IMPORTANT:

Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts.

Only the parameters listed below are used/referenced in this manual for diagnosis. If a scan tool displays other parameters, those values are not recommended by General Motors for use in diagnosis.

If all values are within the expected range described below, refer to Symptoms - Automatic Transmission for diagnosis.

The scan tool values from a properly functioning transmission may be used for comparison with the transmission you are diagnosing. The values below represent a typical display recorded from a properly functioning system.

Scan Tool Data Parameters

Parameter	System State	Expected Value	Description
Operating Conditions: Engine at idle, upper radiator hose hot, closed throttle, transmission in Park, closed loop operation, accessories OFF, brake pedal not applied.
BPP Signal	Applied/Released	Released	This parameter displays the status of the brake switch circuit input. Applied indicates a zero voltage input, brake pedal applied. Released indicates a voltage input, brake pedal released. The scan tool displays Applied or Released.
Calc. Throttle Position	%	0%	This parameter displays a calculated value, which is determined by the accelerator pedal position and the actual throttle position, used to optimize transmission controls. The parameter represents the driver's intended request for torque or acceleration. The range is 0-100%, where 0% represents an idle or coast request and 100% represents a request for wide open throttle (WOT).
Calc. Transmission ISS	RPM	Varies	This parameter displays the rotational calculated speed of the transmission input shaft. The scan tool displays input shaft speed as revolutions per minute (RPM).
Clutch 1 Slip Speed	RPM	Varies	This parameter displays the slip speed of the low 1-2 clutch. The scan tool displays in RPM.
Clutch 1 Status	Applied/Released	-	This parameter displays the commanded state of the low 1-2 clutch. The scan tool displays Applied/Released.
Clutch 2 Slip Speed	RPM	Varies	This parameter displays the slip speed of the Direct 2-3-4 clutch. The scan tool displays in RPM.
Clutch 2 Status	Applied/Released	Varies	This parameter displays the commanded state of the Direct 2-3-4 clutch. The scan tool displays Applied/Released.
Clutch 3 Slip Speed	RPM	Varies	This parameter displays the slip speed of the 4th clutch. The scan tool displays in RPM.
Clutch 3 Status	Applied/Released	Varies	This parameter displays the commanded state of the 4th clutch. The scan tool displays Applied/Released.
Clutch 4 Slip Speed	RPM	Varies	This parameter displays the slip speed of the 1-3 clutch. The scan tool displays in RPM.
Clutch 4 Status	Applied/Released	Varies	This parameter displays the commanded state of the 1-3 clutch. The scan tool displays Applied/Released.
Distance Since First Failure	km (mi)	Varies	This parameter displays the distance in km (mi) since the first failure that caused the DTC was set. The scan tool will display increasing distance as the vehicle is driven.
Distance Since Last Failure	km (mi)	Varies	This parameter displays the distance in km (mi) since the last failure that caused the DTC was set. The scan tool will display increasing distance as the vehicle is driven.
Drvr Axle Torque Request	Numeric	Varies	This parameter displays the drivers requested axle torque as determined by the ECM. The ECM monitors accelerator pedal position and determines how much axle torque is required in order to meet the drivers request. The parameter display range is -8192 to +8191.75 N.m.
Driver Shift Control	Active/Inactive	Inactive	This parameter displays Active or Inactive. The scan tool displays Active when the gear selector is in the sport (S) position, which enables TAP shift. The scan tool displays Inactive when the gear selector is not in the S position, TAP shift disabled.
Driver Shift Request	Upshift/ Downshift/ None/ Invalid	None	This parameter displays the current request from the TAP Shift System. This parameter will display upshift, downshift or invalid, depending on the amount of voltage measured at the remote shift selector input, and will also display none when there is no request.
ECT	°C (°F)	Varies	This parameter displays the input signal from the engine coolant temperature (ECT) sensor. ECT is high at 151°C (304°F) when the signal voltage is low, 0 volt. ECT is low at -40°C (-40°F) when the signal voltage is high, 5 volt.
Engine Run Time	Hours: Minutes: Seconds	Varies	This parameter displays in Hours/Minutes/Seconds, the length of time the engine has been running.
Engine Speed	RPM	Varies	This parameter displays the rotational speed of the engine expressed as revolutions per minute.
Engine Torque	Y (lb ft)	Varies	This parameter displays a calculated value based on engine load, throttle position, mass air flow, and other engine inputs. This parameter is accurate to within 20 N.m (15 ft lb) of actual measured engine torque.
Fail Counter	Counts	0-255	This parameter displays the number of ignition cycles with a failure reported since the first ignition cycle with a failure reported.
Gear Ratio	Ratio	Varies	This parameter displays the actual transmission gear ratio. The scan tool displays the gear ratio calculated from the automatic transmission input shaft speed sensor (AT ISS) and the automatic transmission output shaft speed sensor (AT OSS) inputs.
IAT	°C (°F)	Varies	This parameter displays the temperature of the internal combustion engine (ICE) intake air as determined by the ECM. This display defaults to a set temperature whenever the ECM detects an IAT sensor circuit fault. The parameter display range is -40°C to +215°C (-40°F to +419°F).
Ignition Voltage	Volts	12-14	This parameter displays the system voltage measured at the ignition feed.
IMS	Park, Reverse, Neutral, Drive, Manual, Invalid, or Open	Park	This parameter displays Park, Reverse, Neutral, Manual, or Invalid. The IMS Range display represents a decoded status of the four inputs from the IMS. The combination of IMS inputs are used to determine which position the manual valve is in at any time.
IMS A/B/C/P	HI/Low	Low/Hi/Hi/Low	This parameter displays the status of the four A/B/C/P inputs from the automatic transmission internal mode switch. HI indicates an ignition voltage signal. LOW indicates a 0 voltage signal. The scan tool will display HI/LOW, HI/LOW, HI/LOW, HI/LOW.
Not Run Counter	Counts	0-255	This parameter displays the number of ignition cycles without a pass or a failure reported since the first ignition cycle with a failure reported.
OSS Supply Voltage	OK, Out of Range	OK	This parameter displays OK, Out of Range.
Line PC Sol. CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays whether an open, short to voltage or ground exists in the line pressure control (PC) solenoid valve feedback signal circuit. The scan tool displays OK, Open Short to Volts, Short to GND, or Indeterminate.
Line PC Sol. Pressure Com.	kPa (psi)	Varies	This parameter displays results in kPa (psi).
Output Shaft Direction	Forward / Reverse / Unknown / Invalid	Unknown	This parameter displays the direction of the transmission output shaft speed sensor. The scan tool displays Forward/Reverse/Unknown/Invalid.
Pass Counter	Counts	0-255	This parameter displays the number of ignition cycles with a pass reported and no failures reported since the first ignition cycle with a failure reported.
PC Sol. 2 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
PC Sol. 2 Pressure Cmd.	Yes/No	Varies	This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded.
PC Sol. 3 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
PC Sol. 3 Pressure Cmd.	Yes/No	Varies	This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded.
PC Sol. 4 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
PC Sol. 4 Pressure Cmd.	Yes/No	Varies	This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded.
PC Sol. 5 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
PC Sol. 5 Pressure Cmd.	Yes/No	Varies	This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded.
Shift Sol. 1 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
Shift Solenoid 1	On/Off	On	This parameter displays the commanded state of the reverse, 1st shift solenoid valve (S1). The scan tool displays On/Off.
Shift Sol. 2 CKT Status	OK, Open, Short to GND, Short to Volts, Indeterminate	OK	This parameter displays OK, Open, Short to GND, Short to Volts, or Indeterminate.
Shift Solenoid 2	On/Off	On	This parameter displays the commanded state of the 2-3, 3-4 shift solenoid valve (S2). The scan tool displays On/Off.
TCM Temperature	°C (°F)	Varies	This parameter displays results in °C (°F).
TFP Switch 1	HI/LOW	LOW	This parameter displays the state of the first clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 3	HI/LOW	HI	This parameter displays the state of the 3rd clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 4	HI/LOW	HI	This parameter displays the state of the 4th clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 5	HI/LOW	HI	This parameter displays the state of the fifth clutch oil pressure switch. The scan tool displays HI/LOW.
Trans. Fluid Temp.	°C (°F)	Varies	This parameter displays the input signal of the transmission fluid temperature sensor. Transmission fluid temperature is high, 151°C (304°F), when signal voltage is low, 0 volt. Transmission fluid temperature is low, -40°C (-40°F), when signal voltage is high, 5 volt.
Transmission OSS	RPM	0 RPM	This parameter displays the rotational speed of the transmission output shaft. The scan tool displays output shaft speed as revolutions per minute (RPM).
Vehicle Speed	km/h (mph)	Varies	This parameter displays the rotational speed of the transmission output shaft. The scan tool displays output shaft speed as revolutions per minute (RPM).

Scan Tool Output Controls

Output Control	Description
Shift Solenoid 1 Shift Solenoid 2	The TCM commands Shift Solenoid 1 and Shift Solenoid 2 ON and OFF. When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains On until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. When the engine is running, the following control limits apply: If the engine is running, the message "Engine Running" appears on the scan tool display.
Line PC Solenoid	The scan tool is used to request pressure in increments of 207 kPa (30 psi) from 0-1862 kPa (0-270 psi). The TCM will then command the solenoid to achieve the requested pressure. When the ignition is ON, and the engine is OFF, the pressure request may be controlled within calibrated limits. There are no limits to the output control when the engine is OFF. When the engine is running, the following control limits apply: When the transmission range is Park or Neutral, the pressure request may be controlled within calibrated limits. The engine speed must be less than 1, 500 RPM. If the engine speed is greater than 1, 500 RPM, the message "TR in park/neutral and engine speed over 1, 500 RPM" appears on the scan tool display. When the transmission range is not Park or Neutral, the requested pressure can only be controlled equal to or greater than the pressure determined by the TCM. The TCM does not allow a pressure to be selected that may cause damage to the transmission. If the requested pressure is less than allowed by the TCM, the message "Requested pressure for the Line PC Solenoid is too low" appears on the scan tool display. Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display.
PC Solenoid 2 PC Solenoid 3 PC Solenoid 4 PC Solenoid 5	The TCM commands the pressure control solenoids in order to apply and release the clutches. The TCM commands the pressure control solenoids. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM. When the engine is running, the following control limits apply: If the engine is running, the message "Engine Running" appears on the scan tool display. Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display.