P1738

CODE NUMBER
Scan tool: 75
General scan tool: P1738

CODE NAME
High Temperature Operations Activated

CODE DESCRIPTION
Technical Description
If the transmission oil temperature rises above 115°C (240°F), the overheat shift schedule is activated and the fault code is set. The code is an information fault code only and is being set to aid the technician in determining root cause of a customer driveability issue. The code is also intended to alert the technician to determine if a cooling system malfunction has occurred or if an additional transmission air to oil cooler should be added to the vehicle if the customer regularly drives in a manner that overheats the transmission. Extended operation above 115°C (240°F) will reduce the durability of the transmission and should be avoided. Correcting the cooling system malfunction or installing an additional transmission oil cooler will improve transmission durability especially for customers who operate in city/construction stop and go traffic, tow trailers regularly, drive aggressively in low gear or drive regularly in mountainous areas.

Check Area/Set Conditions
Whenever the engine is running. Immediately once the overheat shift schedule is activated.

Transmission Effects
Overheat shift schedule was activated, no limp-in condition occurs. 2nd gear partial electronically modulated converter clutch (EMCC) above 40 km/h (25 mph), 3rd gear EMCC from 45-69 km/h (28-43 mph) delayed 3-4 upshift at 66 km/h (41 mph), EMCC operation under all conditions above 40 km/h (25 mph) except at closed throttle or 1st gear.


PROBABLE CAUSE
- Transmission overfilled with oil
- Engine cooling fan failure
- Engine thermostat stuck closed
- Radiator corroded or packed with dirt
- Transmission oil cooler plugged
- Customer driving pattern requires additional transmission cooling (See Theory of operation for typical driving patterns that can cause over heating)





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