U3535 code meaning
High Voltage System Interlock Circuit L
Network system Generic code U35xx codes Check engine light
What U3535 means
U3535 is the umbrella code for interlock circuit L, the eleventh loop. Large vehicles carry many guarded compartments. On New Flyer battery buses the energy storage units sit on the roof at front, centre and rear, and each access door is watched by an interlock limit switch. A service instruction from the bus maker, filed with NHTSA, swaps the switch bracket for one with a stop and bonds a striker plate to the door so the switch is pressed reliably; the same procedure turns a separate HV interlock switch off for lockout. A misadjusted door switch, or a lockout switch not turned back on, can open a loop such as L. Which compartments belong to it is not published.
U3535 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 U3535
- Vehicle or one energy storage unit unavailable after maintenance
- High-voltage system warning on the dashboard
- Fault linked to opening or closing a compartment
Common causes of U3535
- Most likelyDoor or lid limit switch on loop L misadjusted or not actuated
- PossibleManual high-voltage interlock or lockout switch left off after service
- PossibleConnector in loop L not fully latched
- Less likelyController monitoring loop L faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hvil loop lHv connectors
What each part of U3535 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 35 | The exact fault in that area. |
What to do next
- Note U3535 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 U3535
What does U3535 mean?
U3535 means "High Voltage System Interlock Circuit L". U3535 is the umbrella code for interlock circuit L, the eleventh loop. It is a generic code, so it means the same on every make.
Is it safe to drive with U3535?
Drive gently and only to a workshop. With U3535 the car can go into limp mode (reduced power) to protect itself.
Will U3535 fail an emissions test?
U3535 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 U3535 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U3535 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.