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Major loss of power, truck wont go faster than 30mph
#21
Jenny alluded to this earlier, but you need to get into the cabin, pull off the right kick panel and find the ECU. Put a multimeter from ground to pin 11 (VTA) of the ECU. With the ignition on but the engine not running, slowly move the accelerator from idle to full open and watch the meter. The voltage should go smoothly from 0 to 5 volts. If it doesn't, you have faulty wiring between the TPS and the ECU, or a faulty TPS. My guess is that you'll see the voltage stuck close to ground.
If either the VCC wire or the ground wire is open between the TPS and the ECU, the TPS signal will be stuck at Gnd or +5V, respectively. If this happens the ECU will be totally confused about what's going on. When you pull the TPS plug off, the TPS signal is pulled to about +2.5 volts by resistors internal to the ECU, allowing the engine to run reasonably, if not optimally.
If the voltage is correct but the engine won't run with the TPS connected, it's possible the ECU is the problem. They rarely fail, but this could be one of those times.
If either the VCC wire or the ground wire is open between the TPS and the ECU, the TPS signal will be stuck at Gnd or +5V, respectively. If this happens the ECU will be totally confused about what's going on. When you pull the TPS plug off, the TPS signal is pulled to about +2.5 volts by resistors internal to the ECU, allowing the engine to run reasonably, if not optimally.
If the voltage is correct but the engine won't run with the TPS connected, it's possible the ECU is the problem. They rarely fail, but this could be one of those times.
Last edited by RJR; 12-04-2014 at 01:42 PM.
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