Auxiliary 5 Volt Supply Output Too Low (Chrysler)
What does P1488 mean?
The P1488 code means the vehicle's onboard diagnostic system has detected: Auxiliary 5 Volt Supply Output Too Low (Chrysler). This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Multiple sensor-related codes stored simultaneously
- Erratic engine idle
- Poor throttle response
- Inaccurate gauge readings
Probable Causes (Ranked by Likelihood)
- Shorted sensor pulling down the 5V reference line Very High
- Damaged wiring in the 5V reference circuit High
- Failed MAP, TPS, or other 5V-powered sensor High
- Water intrusion in a sensor connector Moderate
- Faulty PCM internal 5V regulator Low
Step-by-Step Diagnostic Procedure
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Measure the 5V reference voltage at multiple sensors (MAP, TPS, throttle body). It should be 4.9 to 5.1V with key on engine off.
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If the voltage is low, disconnect sensors one at a time and recheck the 5V line after each one. The shorted sensor will cause the voltage to return to normal when disconnected.
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Inspect all connectors on the 5V reference circuit for water intrusion, corrosion, or bent pins.
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Check the wiring harness for chafing against sharp edges, especially near the exhaust manifold.
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If all sensors test good, the PCM internal 5V regulator may be failing.
Frequently Asked Questions
What is the 5V reference line?
The PCM provides a regulated 5V supply line that powers multiple sensors including the MAP sensor, TPS, and others. If this voltage drops, all sensors sharing that line will give incorrect readings.
Why do multiple codes appear at the same time?
Many sensors share the same 5V reference circuit. When one sensor shorts and pulls the voltage down, all sensors on that circuit report out-of-range values, triggering multiple codes simultaneously.
How do I find the shorted sensor?
Disconnect sensors one at a time on the affected 5V circuit while monitoring the voltage. When you unplug the shorted sensor, the 5V reference will return to its normal level.