U3534High Voltage System Interlock Circuit K High
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3534 reports loop K above its upper threshold. Besides a loop wire chafed onto a 12 V feed, the timing of the electronics can be behind it. In the Texas Instruments reference design TIDA-020069 a 10 mA constant current feeds the loop, and that source can be disabled to save power or to hold the loop in a deliberate fault state until the other systems are ready. Its current then shrinks to one hundredth, and send and return voltages look like a short to battery. If software reads loop K before enabling the source, or the enable line hangs, a high result appears although the wiring is sound. No maker documents U3534. Rule out foreign voltage first, then ask about controller software updates.
- What you may notice
- Vehicle does not become ready
- Fault may appear right at switch-on although no wiring damage is found
- Likely causes
- LikelyLoop K wire in contact with a 12 V supply
- PossibleLoop source still disabled when the controller evaluates loop K
- RareController software with faulty start-up sequence
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.