Mercury MerCruiser Quicksilver 55 Amp Fuse Assembly 79023T56
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Mercury MerCruiser Quicksilver 55 Amp Fuse Assembly 79023T56
Part Number: 79023T56 (service format: 88-79023T56)
Brand: Mercury / Quicksilver
Product Type: High-Current Fuse Assembly (OEM)
System: Engine Electrical / Alternator & Starter-Solenoid Circuit
Fuse Rating: 55 amps
Mounting Hole: Approx. 0.32 in. / 13/32" (10 mm)
Stud Thread: 1/4-28
Quantity Required: 1 per applicable engine
Supersedes: 79023A55, 79023A56
Weight: 70 g
What This Part Does
The 79023T56 is a genuine OEM 55-amp high-current fuse assembly mounted in the alternator and starter-solenoid electrical circuit on selected MerCruiser gasoline engines. It provides overcurrent protection for the engine charging system and electrical harness. If the fuse opens due to an overload, the charging circuit is interrupted until the fuse is replaced and the underlying fault is resolved.
Compatible Applications
Confirm fitment by engine model, serial number, and wiring-harness diagram before ordering. 79023T56 spans several decades of MerCruiser production across multiple engine families.
- MerCruiser 120 GM 153 I/L4
- MerCruiser 140 GM 181 I/L4
- MerCruiser 470 Mercury 224 I/L4
- MerCruiser 165 GM 250 I/L6
- MerCruiser 198 MIE 305 V8
- MerCruiser 228 / 228 MIE 305 V8
- MerCruiser 260 350 V8
- MerCruiser 898 305 V8
- MerCruiser 330 / 330 MIE 454 V8
- MerCruiser 3.0L GM 181 I/L4
- MerCruiser 3.0LX GM 181 I/L4
- MerCruiser 5.0L GM 305 V8 (selected applications)
- Selected Mercury Verado power steering electrical systems
- Selected Mercury outboard high-current electrical circuits
Serial Number Notice
Mercury used visually similar fuse assemblies at different amperage ratings across related applications. These are not interchangeable by appearance — always match the amperage and part number to the engine wiring diagram:
- 55 amp — 79023T56 (this part)
- 110 amp — 79023T10
When to Replace
- Fuse element has opened due to an electrical overload
- Visible heat or burn damage to the fuse body or terminals
- Terminal plate is corroded or distorted
- Attaching stud or terminal area is damaged
- Charging-system diagnosis confirms an open fuse in this circuit
A blown 55-amp fuse should prompt a full inspection of the associated charging and electrical circuit before a replacement fuse is installed. Replacing the fuse without addressing the root cause will result in repeat failure.
Installation Notes
- Disconnect battery power before servicing any high-current fuse circuit
- Inspect all terminals and wiring for corrosion, overheating, loose connections, or shorts before installing the new fuse
- Associated hardware in the same circuit includes fuse-stud nut 21825, lockwasher 26992, and insulating boot 79695T — inspect these during replacement
- Do not substitute a higher-amperage fuse — always match the amperage to what the Mercury wiring diagram specifies for this circuit
- Confirm charging system operation and inspect for leaks or faults after reinstating battery power
Part Number Cross-Reference
- Current OEM: 79023T56 / 88-79023T56
- Supersedes: 79023A55 / 88-79023A55
- Supersedes: 79023A56 / 88-79023A56
Technical FAQ
Q: Can I use a higher-amperage fuse if this one keeps blowing?
A: No. A repeated fuse failure is a symptom of an underlying circuit fault — a wiring short, a failing alternator, or a fault in the starter or charging system. Installing a higher-rated fuse bypasses the protection the circuit was designed with and risks damaging wiring or components. Diagnose and repair the root cause first.
Q: What is the difference between 79023T56 and 79023T10?
A: Amperage rating. The 79023T56 is rated at 55 amps; the 79023T10 is rated at 110 amps. They are used in different circuits and are not interchangeable. Always confirm which amperage your engine wiring diagram calls for at the specific fuse location.
Q: What does the superseded number mean?
A: 79023A55 and 79023A56 are earlier Mercury part numbers for this same fuse assembly. If your older parts list or engine manual shows either of these numbers, 79023T56 / 88-79023T56 is the current OEM replacement.
Parts Desk Insights
Best use case: Order 79023T56 when a charging-system inspection has confirmed the 55-amp fuse is open and you have matched the part number to the engine wiring diagram. It is the correct part for a wide range of older MerCruiser gasoline engines in the alternator and starter-solenoid circuit.
Common issues: The most frequent mistake is ordering by amperage alone without confirming the part number — Mercury’s 55-amp, 90-amp, and 110-amp assemblies look similar but are circuit-specific. A second common issue is replacing the fuse without diagnosing why it failed — a repeat failure almost always points to a fault in the associated wiring, alternator, or starting system that needs to be corrected first.
Related Parts
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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