Control Module Power Supply Voltage Too High
The control module detected a voltage level that exceeds acceptable parameters.
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What it means (plain English)
The control module is seeing a voltage that is too high, usually over 16 volts. This can confuse the system and cause it not to work properly.
What the computer is actually seeing
The control module continuously monitors the voltage supplied to it. If the voltage exceeds 16 volts for more than 5 seconds, it triggers the B1694 code.
What a healthy reading looks like
Normal operating voltage should be between 12.0 to 14.5 volts. Anything over 16 volts is considered too high.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check battery voltage with a multimeter. Expect 12.0 to 14.5 volts when the engine is running.
- 22. Inspect the wiring and connectors for signs of damage or corrosion, especially around the battery and alternator.
- 33. With the engine off, disconnect the positive battery terminal and measure the voltage at the alternator output terminal. Should be less than 16 volts. If it exceeds, the alternator might be faulty or overcharging.
- 44. Inspect the alternator's voltage regulator if the voltage is high. If adjustable, reset to manufacturer's specifications or replace if necessary.
- 55. Reconnect battery and run engine. Monitor voltage again. If it remains high, suspect a bad battery or alternator.
Common causes
- Faulty battery
- Bad alternator
- Wiring issues or shorts
- Failed voltage regulator
- Corroded battery terminals
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may be drivable, but a high voltage can damage electrical components. Fix it soon.
Will this code come back after I clear it?
If the underlying issue isn't fixed, it likely will return.
Why is this code sometimes paired with battery issues?
High voltage can be due to a failing battery or alternator, which also affects power supply to the modules.
Working a real vehicle right now?
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