U3501 code meaning
Control Module Input Power A Circuit Low
What U3501 means
U3501 reports that supply A of a module is below its permitted range. GM's electric brake booster (BSC2) in the 2016–2019 hybrid OBD tables runs two checks: the CAN/logic supply under 7.5 V for 0.09 s, and the internal sensor for the module supply under 4.9 V for 0.2 s, a level below the point where the hardware should already have shut down. Both are Special Type C, so no MIL. The weight of the code lies elsewhere: GM lists U3501 among the conditions that suspend many other booster tests, because motor and sensor checks are meaningless without proper supply. It passes after 30 s with ignition on. Usual causes are a weak or discharged battery, a deep dip while cranking, a corroded fuse or terminal on the feed, or a bad ground.
U3501 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3501
- Module resets or drops off the network at low voltage
- Other self-tests of the module suspended
- Warning lamp for the affected system, usually without MIL
Common causes of U3501
- Most likelyWeak or discharged 12 V battery
- PossibleDeep voltage dip during engine start
- PossibleCorroded fuse, terminal or ground in the A feed
- Less likelyInternal supply stage of the module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Module power aPower wiringFuse
What each part of U3501 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 01 | The exact fault in that area. |
What to do next
- Note U3501 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 U3501
What does U3501 mean?
U3501 means "Control Module Input Power A Circuit Low". U3501 reports that supply A of a module is below its permitted range. It is a generic code, so it means the same on every make.
Is it safe to drive with U3501?
Drive gently and only to a workshop. With U3501 the car can go into limp mode (reduced power) to protect itself.
Will U3501 fail an emissions test?
U3501 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 U3501 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U3501 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.