Chart A2

If a Code EO15 is stored, along with a Code EO21, the cause is probably an open in sensor ground circuit No. 976 (coolant sensor and TPS). To verify this condition, probe the following harness terminals with a voltmeter to 12 volts: coolant temperature sensor terminal "A" (Black/Pink wire) and TPS connector terminal "B" (Black/Pink wire).

If voltage is zero at both sensors, check circuit No. 976 for an open. If wiring is okay, either the ECM connector or the ECM itself is faulty. If 5 volts are present at either sensor, follow the diagnostic chart for each individual code. Diagnose Code EO15, first, and then Code EO21.