B1735 — Mirror Driver Vertical Switch Circuit Short To Battery
**Overview of the code**
The diagnostic trouble code (DTC) B1735 indicates a problem related to the driver’s side mirror vertical adjustment switch circuit, specifically a short circuit to the vehicle’s battery voltage. In simple terms, this means that there’s an unintended electrical connection within the switch wiring that allows current to flow directly to the vehicle’s battery, potentially causing malfunctions or electrical damage.
Note: Different vehicle manufacturers may label or code this issue differently, but the underlying problem remains similar across makes.
**Fast Facts**
- System affected: Mirror adjustment circuit (driver’s side, vertical function)
- Severity: Moderate
- Main symptoms: Mirror adjustment malfunction, warning lights, possible electrical issues
- Driveability: Limited — the vehicle can often be driven, but repairs should be addressed promptly
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**Manufacturer variations for trouble code B1735**
Different vehicle manufacturers often assign their own labels or codes to similar issues. For B1735, some OEMs may use unique diagnostic labels or code descriptions, which can vary widely. Recognising these variations can help technicians quickly identify and resolve the problem.
**Known label variations include**:
- Ford: B1735 – Driver Side Mirror Vertical Adjustment Circuit Short to Battery
- Volkswagen / Audi / Seat / Skoda: 01741 / 01745 – Mirror Adjustment Circuit Fault
- GM / Chevrolet / Buick: Related to mirror control module faults, but some vehicles may use a similar code
- Toyota: Often expressed as a mirror circuit fault in specific wiring diagrams, but may not explicitly label B1735
It’s important to refer to the specific OEM’s repair manual for precise diagnostics and coding.
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**What does trouble code B1735 mean?**
Trouble code B1735 relates to the electrical circuit that controls the vertical adjustment of the driver’s side mirror. The Engine Control Unit (ECU), which is the vehicle’s onboard computer, continuously monitors the operation of various circuits including switches for power windows, mirrors, and other comfort features.
This code indicates that the vertical adjustment switch circuit for the driver’s side mirror has experienced a short circuit to the positive battery voltage. Essentially, the wiring or switch has developed an unintended connection that causes excess current to flow directly from the power source to the circuit, often due to damaged wiring, a faulty switch, or an internal short.
The code typically appears when the ECU detects this abnormal electrical condition during system checks or when the driver attempts to adjust the mirror. It can occur suddenly or develop over time, especially if wiring insulation becomes brittle or switches malfunction.
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**Severity and risks of trouble code B1735**
This DTC signifies a moderate electrical issue that could pose several risks if left unaddressed:
– **Electrical component damage**: Continuous short circuit can cause overheating or damage to wiring, connectors, and control modules.
– **Malfunction of mirror adjustment**: The mirror might become stuck, unable to move vertically, impairing driver visibility.
– **Potential safety concern**: Inability to properly adjust mirrors could reduce driving safety, especially in changing traffic or weather conditions.
– **Battery drain or electrical fires**: Although rare, persistent short circuits increase the risk of drained batteries or, in extreme cases, electrical fires.
**Can the vehicle be driven?**
**Limited —** You can generally drive the vehicle, but it is always recommended to address this issue promptly to prevent further damage.
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**Symptoms of trouble code B1735**
Typical symptoms associated with this fault include:
– Inoperative or unresponsive driver’s side mirror adjustments (specifically in the vertical direction).
– Warning lights related to the vehicle’s electrical system or mirror controls.
– Intermittent or constant malfunction indicator lamp (MIL) illumination on the dashboard.
– Possible flickering or electrical noise from the mirror area.
– In some cases, other electrical circuits may exhibit faults if the wiring is compromised.
It’s important to note that the symptoms can vary depending on the vehicle’s design and severity of the short circuit.
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**Most likely causes of trouble code B1735**
Understanding the root causes of this fault is key to effective repair. The causes are generally ranked from most common to less frequent:
1. **Wiring Damage or Short Circuit**
The most typical cause is damage to the wiring harness leading to the driver’s mirror switch. This can occur as a result of abrasion, pinched wiring, or corrosion at connectors, leading to a direct short to the positive battery voltage.
2. **Faulty Mirror Adjustment Switch**
The switch itself might be internally faulty or worn out, causing an internal short circuit. This is especially likely if the switch shows signs of physical damage or has been subjected to water ingress.
3. **Inappropriate Repairs or Modifications**
Previous repair attempts involving wiring splices or unauthorized modifications may introduce unintended electrical connections, resulting in shorts.
4. **Internal Mirror Module Fault**
Some modern mirrors include integrated electronic modules; malfunction or internal component failure could cause circuit faults that breach the circuit’s insulation.
5. **Corrosion or Water Damage**
Moisture ingress into the mirror assembly or wiring connectors can corrode contacts and cause shorts, especially in regions with high humidity or road salt.
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**How to diagnose trouble code B1735**
Diagnosing this fault requires a methodical approach to identify the exact cause:
1. **Visual Inspection**
Begin with a thorough inspection of the wiring harness connected to the driver’s side mirror. Look for signs of damage, frayed insulation, corrosion, or loose connectors.
2. **Check the Mirror Switch**
Test the switch for proper function and inspect for signs of corrosion, moisture, or physical damage.
3. **Use Live Data and Circuit Testers**
Connect a suitable multimeter or scan tool to monitor the circuit while operating the switch. Check for voltage levels, continuity, and abnormal resistance values.
4. **Inspect Electrical Connectors**
Disconnect the mirror wiring connector and inspect for bent pins, corrosion, or debris. Clean or repair as necessary.
5. **Perform Continuity Tests**
With the circuit disconnected, test for continuity between the switch terminal and the battery positive terminal to identify potential shorts.
6. **Compare with Manufacturer Wiring Diagram**
Consult the vehicle’s wiring diagram to ensure correct wiring and identify possible splices or modification points contributing to the fault.
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**Possible repairs for trouble code B1735**
Based on diagnostic findings, repairs may involve:
– **Repair or replace damaged wiring or connectors** (Basic repair, suitable for a trained DIYer).
– **Replace the mirror adjustment switch** if internal fault or wear is confirmed (Professional repair recommended).
– **Reinstall or repair wiring harnesses** that are pinched, corroded, or improperly routed (Basic to professional, depending on extent).
– **Address water ingress or corrosion** by cleaning contacts and sealing mirror assemblies properly (Basic repair).
– **Replace the entire mirror assembly** if internal damage or circuit faults cannot be repaired (Professional repair).
– **Remove unauthorized modifications or splices** in the wiring and restore original wiring integrity (Professional repair).
Addressing the root cause promptly prevents further wiring damage and ensures the mirror functions reliably.
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**Vehicles commonly associated with trouble code B1735 in Europe**
This fault has been reported across various vehicle makes and models, especially those with power-operated mirrors. The issue is more prevalent among vehicles manufactured in regions with harsh climates or extensive use of road salt.
**Common brands and engine families affected include**:
– **Ford**: Focus, Fiesta, Kuga, with models from certain production years.
– **Volkswagen Group**: Golf, Passat, Tiguan, Skoda Octavia, Seat Leon.
– **GM / Opel / Vauxhall**: Astra, Corsa, Astra J.
– **Toyota**: Corollas, RAV4, and other models with electric mirror adjustment.
The specific model and year variations are abundant, but the commonality lies in the design of electric mirrors and their wiring harnesses.
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**Frequent mistakes & best practices**
When diagnosing or repairing B1735, common pitfalls include:
– **Assuming the problem is solely the switch** without inspecting wiring; often, damage lies in the harness.
– **Misdiagnosing the short circuit as a faulty module** when wiring or connectors are the true cause.
– **Using unqualified repair techniques** that do not address the actual wiring or component failure.
– **Ignoring water damage or corrosion**, which can cause intermittent faults and are often overlooked.
**Best practices**:
– Always perform a visual inspection first.
– Use the correct wiring diagram to verify wiring routes.
– Test circuit continuity and voltage in live conditions.
– Replace damaged wiring or connectors with OEM-approved parts.
– Confirm the repair by clear testing before finalising.
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**FAQ — trouble code B1735**
**Can this code disappear on its own?**
No, the fault persists until the root cause (damaged wiring, switch, or module) is properly addressed.
**Can I keep driving?**
While the vehicle can often still be driven, it’s advisable to repair the issue quickly to avoid further electrical damage or safety concerns related to mirror adjustability.
**Why does the code return after clearing it?**
If the underlying wiring damage or component fault remains, the ECU will detect the short and re-trigger the code once the system performs its self-test routines.
**Is this a common problem?**
It’s relatively common in vehicles with electric mirrors, especially in environments with harsh weather, where wiring or switches are subject to wear, corrosion, or damage.
**Should I seek professional help?**
Yes, especially if you’re unfamiliar with electrical testing and circuit diagnosis. A professional technician can accurately pinpoint the cause and perform necessary repairs safely.
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This comprehensive guide aims to educate both technicians and vehicle owners about the nature, diagnosis, and repair of the B1735 trouble code. Addressing electrical circuit faults promptly ensures the longevity of vehicle components and maintains safe driving conditions.