Chart C-16B Coolant Level Switch

Chart C-16B Coolant Level Switch:

Coolant Level Switch:

CIRCUIT DESCRIPTION
The coolant level switch is an assembly containing a reed switch and magnetic float. When the coolant level is normal, the float rests away from the reed switch, causing the switch to open. When the coolant level is low, the float rests near the reed switch and the switch closes.

The coolant level switch is mounted in the radiator surge tank to monitor radiator coolant level. the coolant level switch is a normally open switch. If coolant falls below a specified level, the switch closes sending a ground signal to the Powertrain Control Module (PCM). The PCM in turn will send information through serial data to the instrument cluster (IPC). The Instrument Panel Cluster (IPC) will then turn "ON" the coolant level telltale.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. The coolant level switch cannot be removed from the surge tank. Draining the coolant from the tank will check if the switch can detect an empty tank and also check the PCM and wiring.
2. This step will simulate normal coolant level. If the telltale turns "OFF" when the coolant level switch is disconnected, the PCM, IPC and wiring are OK.
3. The PCM uses a voltage signal to sense when the coolant signal circuit is pulled low by the coolant switch. If voltage is not present on this the signal circuit, then the circuit is open, or connections or the PCM are faulty.
4. A test light is used to determine if the coolant level indicator is remaining "ON" because of a shorted signal wire or faulty PCM or IPC. If the test light is "ON", then the signal circuit is shorted to ground.
5. This step will determine that the battery voltage seen on the signal circuit was from the PCM and not a wire shorted to voltage.
6. The PCM sends coolant level information through serial data to the IPC. If the Tech 1 scan tool indicates low coolant level with the coolant level switch electrical connector disconnected, the the PCM is faulty.

DIAGNOSTIC AIDS
Quick test:

^ Disconnect coolant level switch electrical connector. With a test light connected to ground, probe the signal circuit. This will cause the coolant level indicator to turn "ON" if the wiring, PCM and IPC are OK.
^ An "Intermittent" problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.
^ Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.