SL L4-1.9L SOHC VIN 9 (1991)
FIGURE 2
Description:
The engine cooling fan and hot telltale lamp are controlled by the powertrain control module (PCM). The PCM monitors the coolant
temperature indicator - PCM sensor (CTS) that is located on the lower left, rear side of the cylinder head (Figure 2) and will turn on
the engine cooling fan when the coolant temperature reaches approximately 105.5~C (222~F). This sensor is connected to the PCM
by two wires. The coolant temperature gage is controlled by the single wire engine coolant temperature indicator sensor that is located
on the upper left, rear side of the cylinder head (Figure 2).
FIGURE 1
During certain conditions (hot days, under heavy vehicle loads, air conditioning on, pulling a trailer, extended idling, etc.), the coolant
temperature gage may read higher than the normal range indicated in Figure 1. This is normal for high-ambient and load conditions. If
the coolant temperature gage reads at, or on the RED zone, or if the hot telltale lamp comes on, there is a concern and the following
procedures must be performed to diagnose and correct this condition.
1. Verify that no diagnostic codes are present in the current or malfunction history of the PCM.
2. Inspect the engine cooling system. Refer to "Cooling System" section of the "Engine Mechanical Service Manual."
3. Verify proper engine cooling fan operation. Monitor the engine cooling fan with the portable diagnostic tool (PDT). The engine