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Makes 🢒 Chevrolet 🢒 1998 🢒 Cavalier 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Powertrain Control Module Controlled Warning Lamps Diagnosis

Powertrain Control Module Controlled Warning Lamps Diagnosis Coolant Level Switch Diagnosis


Object Number: 52880 Size: MF
Engine Controls Components
IAC Valve, Generator, TR, Oil, and Coolant Switches
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Diagnosis
    • The following tables will diagnose the oil pressure switch and the coolant level switch circuits.
    • For diagnosis of the Instrument Panel Cluster (IPC), refer to Diagnostic System Check - Instrument Cluster in the Instrument Panel, Gauges, and Console portion of the service manual.
    • For PCM replacement information, refer to PCM Replacement .

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. If the coolant level falls below a specified level, the switch closes sending a ground signal to the Powertrain Control Module (PCM). The PCM will then send this signal to the instrument panel cluster (IPC). The IPC will then illuminate the low coolant level telltale lamp.

Diagnostic Aids
    • Quick Test: Disconnect the 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.
    • Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following items:
       - Backed out terminals
       - Improper mating
       - Broken locks

Test Description

Numbers below refer to the step numbers on the Diagnostic Table.

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

    2.

  2. 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.

    3.

  3. A test light is used to determine if the coolant level telltale lamp is remaining ON because of a shorted signal circuit, a malfunctioning PCM, or a malfunctioning IPC. If the test light is ON, then the signal circuit is shorted to ground.

    4.

  4. This simulates a normal coolant level. If the telltale lamp turns OFF when the coolant level switch is disconnected, then the PCM, the IPC and the wiring are OK.

    5.

  5. 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 malfunctioning.

    6.

  6. This will determine that the battery voltage seen on the signal circuit was from the PCM and not a wire shorted to voltage.

    7.

  7. The PCM sends coolant level information through serial data to the IPC. If the scan tool indicates a low coolant level when the coolant level switch electrical connector disconnected, then the PCM is malfunctioning.

    8.

  8. Reprogram the replacement PCM. Perform the crankshaft position system variation procedure. Refer to PCM Replacement/Programming for PCM reprogramming and CKP System Variation Learn Procedure for the crankshaft position system variation procedure.

    9.

  9. If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.

Coolant Level Switch

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check for 2.4L or Powertrain On Board Diagnostic (OBD) System Check for 2.2L

2
  1. Turn ON the ignition switch leaving the engine OFF.
  2. Install a scan tool.
  3. Check for DTC U1016 with the scan tool.

Was DTC U1016 set?

--

Go to DTC U1016 Serial Communications Malfunction for 2.4L or DTC U1016 Serial Communications Malfunction for 2.2L

Go to Step 3

3
  1. Turn OFF the ignition switch.
  2. Wait 10 seconds.
  3. Turn ON the ignition switch leaving the engine OFF.

Did the coolant level telltale lamp on the instrument panel cluster turn ON for about 3 seconds then turn OFF and stay OFF?

--

Go to Step 4

Go to Step 5

4

Drain the coolant from the surge tank.

Did the coolant level telltale on the instrument panel cluster turn ON?

--

Go to Step 20

Go to Step 6

5

Check the coolant level in the surge tank.

Is the coolant level OK?

--

Go to Step 7

Go to Step 8

6

  1. Disconnect the coolant level switch electrical connector from the switch.
  2. Connect a test light to B+.
  3. Probe the engine coolant level switch ground circuit with the test light.

Does the test light illuminate?

--

Go to Step 9

Go to Step 10

7

Disconnect the coolant level switch electrical connector.

Is the coolant level indicator lamp illuminated?

--

Go to Step 11

Go to Step 17

8

Fill the surge tank.

Is the action complete?

--

Go to Step 2

--

9

  1. Connect a DMM to ground.
  2. Probe the coolant level switch signal circuit with the DMM.

Does the DMM read the specified value?

B+

Go to Step 12

Go to Step 13

10
  1. Check the coolant level switch ground circuit for the following condition(s):
    2. • Poor electrical connection
    • Open circuit
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 20

--

11
  1. Connect a test light to B+.
  2. Probe the coolant level indicator switch signal circuit with the test light.

Does the test light illuminate?

--

Go to Step 14

Go to Step 15

12

  1. Connect a test light to ground.
  2. Probe the coolant level indicator switch signal circuit with the test light.

Does the test light illuminate?

--

Go to Step 16

Go to Step 17

13
  1. Check the coolant level switch signal circuit for the following condition(s):
    2. • Poor electrical connection
    • Open circuit
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 20

Go to Step 19

14
  1. Check for a short to ground in the coolant level switch signal circuit
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 20

Go to Step 19

15

Check the coolant level indicator with the scan tool.

Is the coolant level indicated as low?

--

Go to Step 19

Go to Step 18

16
  1. Check for a short to B+ in the coolant level switch signal circuit.
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 20

Go to Step 19

17
  1. Turn OFF the ignition switch.
  2. Replace the engine coolant level switch.

Is the action complete?

--

Go to Step 20

--

18
  1. Turn OFF the ignition switch.
  2. Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Is the action complete?

--

Go to Step 20

--

19

  1. Turn OFF the ignition switch.
  2. Check for poor electrical terminal connection(s) at the PCM.
  3. If the electrical connection(s) are OK, then replace the PCM. Refer to PCM Replacement .

Is the action complete?

--

Go to Step 20

--

20

Operate the vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

--

System OK

Go to Step 2