Code
B1529
ALFA ROMEO
B — Body
Memory disable switch short to positive
Views:
UK: 5
EN: 8
RU: 4
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring contacting a +12V source
- Corroded or damaged switch connector or terminals
- Faulty memory-disable switch (internal short)
- Incorrect/loose aftermarket accessory wiring tied to the circuit
- Faulty body/comfort module or input circuit within the control module
- Blown or incorrect fuse supplying the circuit
Symptoms
- Memory functions (seat/radio/mirror presets) disabled or not working
- Related memory-disable switch is inoperative or stuck in one state
- DTC B1529 stored in body/control module and may illuminate related warning or message
- Intermittent or permanent loss of memory functionality
What to check
- Read stored DTCs and freeze frame data with a capable scan tool
- Obtain wiring diagram and connector pinout for the memory-disable switch circuit
- Visually inspect switch, connector and harness for damage, chafing, pin corrosion or water ingress
- Check for signs of recent aftermarket installations near the harness and switch
- Inspect fuses and related power feeds for the circuit
Signal parameters
- Expected: switch signal should be either open/low (0V) or switched to ground depending on design; it should NOT be a constant +12V when switch is inactive
- Observed for B1529: constant ~12V present on the switch signal line when it should be low/open
- Check both at the switch connector (with connector disconnected) and at the module input to localize fault
Diagnostic algorithm
- Retrieve and record DTCs, freeze frame and lamp status with a scan tool; confirm B1529 is present.
- Obtain the vehicle wiring diagram and identify the memory-disable switch circuit, power feed, ground and connector pinouts.
- Visually inspect the switch, connector and harness for damage, corrosion, pin push-out or signs of rubbing to chassis or other +12V sources.
- With ignition ON, backprobe the switch signal wire at the connector (with switch connected) and measure voltage: note state with switch operated and released.
- Disconnect the switch and measure voltage on the harness signal pin. If ~12V is still present with switch disconnected, there is a short to positive upstream (harness or accessory).
- If voltage is low/0V with switch disconnected but high when switch connected, suspect a short inside the switch and replace the switch.
- If the harness is shorted, trace wiring toward the origin: flex harness along route, unplug intermediate connectors, inspect for rubbed-through insulation or aftermarket splices tied into a constant +12V feed; repair or replace damaged sections.
- If wiring and switch check OK, test the module input (consult service manual for pin resistance/power checks). Suspect module failure if input is shorted internally — verify with manufacturer procedures before replacing module.
- After repair, clear codes and verify operation with a test drive/cycle and re-scan to confirm B1529 does not return.
Likely causes
- Wiring harness shorted to a fused +12V feed (most common)
- Damaged/contaminated switch connector or pin
- Failed memory-disable switch
- Aftermarket alarm/seat/comfort device incorrectly wired into circuit
- Module input fault (least common)
Fault status
Status
Memory disable switch circuit — short to positive (+12V) detected on input. Fault stored in body/control module.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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