U3502 code meaning
Control Module Input Power A Circuit High
Network system Generic code U35xx codes Check engine light
What U3502 means
U3502 means supply A rises above its allowed limit. In GM's 2016–2019 hybrid OBD tables the electric brake booster checks its CAN supply voltage and sets U3502 above 16 V lasting 0.09 s while its software runs; this is Type B, so the MIL comes on after two failing trips, and the test passes after 30 s with ignition on. Unlike low voltage, which a module can often ride out, overvoltage endangers electronics and power stages, which explains the short reaction time. Common causes are a regulator fault in the generator or DC/DC converter, jump-starting from a 24 V source or a wrongly set charger, and a load dump when a battery cable comes loose while charging. If several modules report high voltage at the same moment, the charging system is at fault, not the module.
U3502 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3502
- MIL after repeated trips
- Several modules logging overvoltage at once
- Flickering lights or battery warning
Common causes of U3502
- Most likelyGenerator regulator or DC/DC converter overcharging
- PossibleJump start or external charger with excessive voltage
- PossibleLoose battery terminal causing voltage spikes
- Less likelyFaulty voltage measurement inside the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Module power aCharging system
What each part of U3502 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 02 | The exact fault in that area. |
What to do next
- Note U3502 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U3502
What does U3502 mean?
U3502 means "Control Module Input Power A Circuit High". U3502 means supply A rises above its allowed limit. It is a generic code, so it means the same on every make.
Is it safe to drive with U3502?
Drive gently and only to a workshop. With U3502 the car can go into limp mode (reduced power) to protect itself.
Will U3502 fail an emissions test?
U3502 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U3502 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U3502 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.