Electronic Throttle Control Supply Voltage Too High (Ford)
What does P1659 mean?
The P1659 code means the vehicle's onboard diagnostic system has detected: Electronic Throttle Control Supply Voltage Too High (Ford). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Erratic idle speed
- Throttle surge or hesitation
- Limp mode activation
- Engine power reduced message
Probable Causes (Ranked by Likelihood)
- Overcharging alternator Very High
- Faulty voltage regulator High
- Short circuit in throttle body wiring Moderate
- Defective PCM voltage regulator circuit Low
Step-by-Step Diagnostic Procedure
-
Measure charging system voltage with engine running; should be 13.5-14.5V. Over 15V indicates overcharging.
-
Test the voltage regulator or alternator output with a load tester.
-
Inspect throttle body wiring for shorts to battery voltage or chafing against metal.
-
Measure the 5V reference circuit at the throttle body connector; it should not exceed 5.1V.
-
If alternator and wiring check out, test PCM internal voltage regulator by measuring output at various loads.
Frequently Asked Questions
Can an overcharging alternator damage my throttle body?
Yes. Excessive voltage can damage the throttle body electronics and other sensitive modules. Replace the alternator or voltage regulator promptly.
What voltage is too high for the throttle system?
The 5V reference circuit should stay between 4.8V and 5.1V. System voltage above 15V from the alternator is also problematic.
Will this code cause my vehicle to go into limp mode?
Yes. The PCM protects the engine by limiting throttle opening when supply voltage is out of range.