DTC 87

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The control module calculates ratio based on the transmission input speed and output speed sensor readings. The control module compares the known transmission ratio to the calculated ratio, for the particular gear range selected.

DTC 87 WILL SET WHEN
^ No DTC(s) 21, 22, 24, 28, 71, 72 and 74.
^ TP is greater than 25%.
^ Not in P/R/N.
^ Engine speed is greater than 300 RPM.
^ Vehicle speed is greater than 7 mph.
^ Transmission temperature is greater than 20°C.
^ Trans gear ratio is greater than 1.42 in 3rd or 4th gear.
^ All conditions met for 2 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
^ 2nd gear.
^ Line pressure set to maximum.
^ Inhibit Torque Converter Clutch (TCC) operation.

DTC 87 WILL CLEAR WHEN
The fault condition no longer exists, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. An out of range trans range pressure switch could falsely indicate the actual transmission range.
2. This test compares the known ratio for a commanded gear to the calculated ratio displayed on the scan tool.

DIAGNOSTIC AIDS
This DTC will set when trans commanded gear is 3 or 4 and trans is mechanically in 1st or 2nd gear. DTC 81 is used to detect a 2-3 shift solenoid circuit malfunction.