U3514 code meaning
High Voltage System Interlock Circuit B High
Network system Generic code U35xx codes Check engine light
What U3514 means
U3514 means loop B reads higher than allowed: a wire of the loop touches 12 V or another supply, or the loop does not fall back to its low state once the module turns its source off. GM's loop A code checks both states, allowing 24 % of 5 V while the source is off and 44 % while it is on. Ford's interlock patent tests the source line for a short to 12 V before releasing the loop, then stores a trouble code and turns on the Service Soon lamp rather than a general warning. In the reference design from Texas Instruments a short to battery shows up as loop current that no longer follows the commanded on/off pattern. No manufacturer lists U3514 itself. Disconnecting segments one at a time shows where the foreign voltage enters loop B.
U3514 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3514
- Vehicle will not start or enter ready mode
- Service or HV warning lamp on
- Fault stays present with all HV connectors properly mated
Common causes of U3514
- Most likelyInterlock wire of loop B shorted to 12 V or another supply
- PossibleInterlock source in the module not switching off
- PossibleWater in a connector bridging an interlock pin to a supply pin
- Less likelyIncorrect splice or add-on wiring after a repair
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hvil loop bHvil wiring
What each part of U3514 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 14 | The exact fault in that area. |
What to do next
- Note U3514 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 U3514
What does U3514 mean?
U3514 means "High Voltage System Interlock Circuit B High". U3514 means loop B reads higher than allowed: a wire of the loop touches 12 V or another supply, or the loop does not fall back to its low state once the module turns its source off. It is a generic code, so it means the same on every make.
Is it safe to drive with U3514?
Drive gently and only to a workshop. With U3514 the car can go into limp mode (reduced power) to protect itself.
Will U3514 fail an emissions test?
U3514 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 U3514 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U3514 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.