1986 Nissan 300ZX Steering Column: Diagnosing Electrical Faults and Mechanical Looseness

Understanding Steering Column Failures in the 1986 300ZX

When diagnosing issues related to the steering column in a 1986 Nissan 300ZX (Z31), problems typically fall into two categories: electrical failures originating from the combination switch, or mechanical wear causing looseness and play. While the main column assembly is a durable mechanical part, the components attached to it are far more likely to fail with age. This guide will help you distinguish between these issues, identify the correct parts, and know what to look for in a used replacement.

Symptoms of Failure

Diagnosing the problem starts with identifying the specific symptoms. Is the issue electrical, mechanical, or both?

Electrical Symptoms (Usually a Bad Combination Switch)

• Headlights, Turn Signals, or Wipers Don't Work: One or more functions controlled by the column stalks may fail completely or work intermittently. For example, your headlights might not turn on, or your turn signals may not flash.
• Functions Work in Some Positions But Not Others: You might find that the high beams work but the low beams don't, or the wipers only work on one speed. This points to worn internal contacts in the switch.
• Lights Turn On By Themselves: A classic Z31 issue is finding the running lights on even when the car is off, draining the battery. This is caused by a short or worn contacts inside the combination switch.
• Stalk Feels Loose or Broken: The physical stalks for the wipers or turn signals may feel flimsy, crack, or break off.

Mechanical Symptoms (Column, Shaft, or Bushing Wear)

• Steering Wheel Play or "Slop": A noticeable amount of play where you can turn the steering wheel slightly before the front wheels respond. This is often caused by worn-out universal joints (U-joints) on the steering shaft that connects the column to the rack.
• Crooked Steering Wheel: The steering wheel may be off-center while driving straight, and its position might even change after making turns. This can be a sign of worn U-joints binding and releasing.
• Clunking or Grinding Noises: You may hear noises from the column area when turning the wheel, indicating worn bearings or a failing U-joint.
• Wobbly Steering Wheel: If the entire wheel feels loose and can be moved up-and-down or side-to-side, the tilt mechanism's internal bolts or the main column bearings may be worn.

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

While there are no major recalls specifically for the 1986 300ZX steering column, Nissan did issue a voluntary recall campaign for 1984 models concerning contaminated grease in the headlight switch, which could cause the lights to fail. This highlights a history of electrical issues with the combination switch assembly in the Z31 platform. Other recalls for the 1986 model year relate to the fuel system and automatic transmission but not the steering column.

Forum discussions among Z31 owners are the best source of information, confirming that combination switch failure and worn steering shaft U-joints are the most common and well-documented problems for these vehicles.

Buying a Used Steering Column Assembly

Since new OEM steering columns and combination switches for the 1986 300ZX are largely discontinued and can be extremely expensive if found, a quality used part is often the only practical solution. Here’s what to inspect before buying:

1. Verify Compatibility (This is Critical)

The 1986 300ZX had several variations that affect which column or switch you need. You MUST match the part to your car's original equipment:

• Trim Level: Parts can be specific to GL, GLL, or SF (Canadian) trims.
• Instrument Cluster: The wiring is different for cars with the analog instrument cluster versus the optional digital dash.
• Part Numbers: Cross-reference the part numbers from your old unit if possible. The main column assembly is typically a 48810-xxxxx number, while the combination switch is a 25560-xxxxx or B5560-xxxxx number. Don't be afraid to ask the seller for clear pictures of any part numbers or tags.

2. Physical Inspection Checklist

• Combination Switch Stalks: Inspect the plastic stalks for cracks, stress marks, or a loose, floppy feel. Test the rotational and push/pull functions. They should click into each position with a positive feel.
• Electrical Connectors: Carefully examine all electrical plugs and the wiring harness. Look for any cut wires, corroded pins, or cracked plastic connectors. A damaged harness is a major red flag.
• Tilt Mechanism: If possible, test the tilt lever. The column should move smoothly and lock firmly into each position without any wobble.
• Steering Shaft U-Joints: If the lower shaft is included, grab both ends of the U-joint and try to twist them. There should be no discernible play or notchiness. The joint should move smoothly in all directions.
• Overall Condition: Look for signs of heavy corrosion, impact damage, or unauthorized modifications. A clean part from a low-mileage, well-kept donor car is always preferable.

Cost Comparison

Replacing the steering column or its components involves varied costs depending on the part needed and the approach taken.

Replacement Difficulty

Working on the steering column requires care, especially when dealing with the steering wheel and electrical systems.

• Combination Switch Replacement: Difficulty: 3/5. This is a feasible DIY job for someone with moderate mechanical skill. It involves removing plastic shrouds, the steering wheel (which requires a steering wheel puller), and unplugging connectors before unscrewing the switch assembly.
• Full Column Replacement: Difficulty: 4/5. This is a much more involved job. In addition to the steps above, you must disconnect the U-joint in the driver's footwell and unbolt the entire column assembly from under the dashboard. Access can be tight.

Frequently Asked Questions (FAQ)