USING AN ANALOG VOLTMETER
Key ON Engine OFF Test
See Figure 1
- With the ignition switch in the OFF position, connect a jumper wire between circuits 60 and 201 on the self-test connector.
- Connect the analog voltmeter from the battery positive post to the self-test output connector.
- Self the voltmeter scale to 0-15 volt range.
- Turn the ignition switch ON , but do NOT start the engine. One quick initialization pulse may occur. The output codes will follow in about 5 seconds.
- Count the voltmeter sweeps, to determine which codes are being transmitted.
- The MCU system uses 2-digit codes with the pause between each digit being about 2 seconds long. The pause between the two different codes is about 4 seconds long. The code group is sent twice. This allow you to check the accuracy of the codes as you record them.
- Once this test has been performed and all fault codes recorded, you can refer to the "Code Descriptions" in this guide for the meaning of the fault code(s).
See Figure 2
- Turn OFF all electrical equipment and accessories in the vehicle.
- Follow all safety precautions during testing.
- Make sure all fluids are at the proper levels.
- Perform a "Visual Inspection" as detailed earlier in this guide.
The following steps involve servicing the engine with the engine running. Observe all safety precautions and perform the steps as follows:
Apply the parking brake.
- The engine should be at normal operating temperature for this test. If not, start the engine and let it idle, until the engine reaches normal operating temperature. This is when the upper radiator hose is Hot and engine RPM has dropped to its normal warm idle speed and repeat Key ON Engine OFF test again.
- If engine is warm, after the codes have been retrieved, Start the engine.
Extract the fault codes as follows:
- Start the engine and raise idle to 3000 rpm within 20 seconds of starting vehicle.
- Hold the idle at 3000 rpm until codes are sent.
- When codes are sent release throttle and let engine return to idle speed.
- If your vehicle is equipped with a knock sensor perform the following test, if not skip to Step 10.
Simulate a spark knock by placing a 3 / 8 inch socket extension (or similar tool) on the manifold near the base of knock sensor. Tap on the end of extension lightly with a 2-6oz. hammer for approximately 15 seconds. Do NOT hit on the knock sensor itself. Count the voltmeter's needle sweeps to determine which codes are being sent.
- The first series of sweeps should be the engine ID code; ignore any sweeps that last any longer than 1 second. The engine ID code will be 1 / 2 the number of cylinders. Specifically, confirmation of a 4-cylinder engine would appear as 2 needle sweeps.
- If no sweeps occur, repeat KOER test procedures, starting with Step 1. If the meter still does not sweep, you have a problem which must be repaired before proceeding.
- Count the sweeps on the meter to find out which codes are being sent. All codes are 2 digits long and will appear the same way as in KOEO Self-Test. Ignore any sweeps lasting more than 1 second. Write codes down on a piece of paper; codes will be sent twice so you can check your list for accuracy. Write codes down in the order they appear. Turn the ignition switch OFF when codes are finished and remove the jumper wire.