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Sierra Replacement Mercury Outboard Control Module
Mercury V135, V140, V150, V200, XR-6 & 140 Jet Control Module - Sierra 18-99253
The Sierra 18-99253 Control Module is an aftermarket replacement for select Mercury outboard engines using Mercury 857185T1 and related control module applications.
Verified fitment includes select V-135, V-140, V-150, V-200, XR-6 / Magnum III and 140 Jet Mercury outboards.
The original Mercury OEM version of this module is no longer available. Sierra 18-99253 is the available replacement option for these applications.
Mercury has discontinued the original OEM control module used in these applications.
The Sierra 18-99253 is the available replacement for compatible engines that originally used Mercury 857185T1.
OEM & Cross Reference Numbers
| Brand / Type | Part Number |
|---|---|
| Sierra | 18-99253 |
| Cross Reference | 144-7185 |
| Mercury OEM | 857185T1 |
Mercury Outboard Fitment
| Mercury Engine | Serial Number Range |
|---|---|
| V-135 | 0G960500 thru 0T178499 |
| 140 Jet | 0G960500 thru 0T178499 |
| V-140 International | 0T178500 thru 1B226999 |
| V-150 | 0G960500 thru 1B226999 |
| XR-6 / Magnum III | 0G960500 thru 1B226999 |
| V-200 | 0G960500 thru 1B226999 |
Mercury used different electrical components across similar horsepower ranges. Do not order this control module by horsepower alone.
Verify the complete engine serial number and confirm the original module cross references 857185T1 or 144-7185 before ordering.
What This Control Module Does
The control module is part of the engine's electronic control system and helps manage the electrical functions assigned to the module within the Mercury outboard ignition / engine management system.
A failed control module can result in ignition or engine-running issues depending on the exact engine configuration and failure mode.
Common Reasons for Replacement
- Original Mercury module has failed
- Intermittent ignition or engine electrical problem
- Module has visible heat or electrical damage
- Diagnostic testing identifies the module as faulty
- Original Mercury 857185T1 is no longer available
Before Replacing the Module
Electronic control modules should not be replaced solely based on symptoms. Verify related wiring, grounds, connectors, stator / trigger components, charging voltage and other ignition-system components as applicable to the engine.
Follow Mercury service procedures for the exact engine and serial number before condemning the module.
Why Use Sierra 18-99253?
- Sierra aftermarket replacement control module
- Replaces discontinued Mercury OEM 857185T1
- Cross references 144-7185
- Fits select Mercury V-135 outboards
- Fits select Mercury V-140 International outboards
- Fits select Mercury V-150 outboards
- Fits select Mercury V-200 outboards
- Fits select Mercury XR-6 / Magnum III engines
- Fits select Mercury 140 Jet applications
- Available replacement now that the OEM module is discontinued
FAQ
Is Sierra 18-99253 an OEM Mercury part?
No. This is a Sierra aftermarket replacement.
What Mercury part number does 18-99253 replace?
It replaces Mercury 857185T1 and cross references
144-7185.
Is the original Mercury control module still available?
No. The Mercury OEM version is no longer available.
Sierra 18-99253 is the available replacement for compatible applications.
Does it fit Mercury V-150?
Yes. Verified fitment includes V-150 engines from
0G960500 thru 1B226999.
Does it fit Mercury XR-6?
Yes. Verified XR-6 / Magnum III fitment includes serial
0G960500 thru 1B226999.
Does it fit Mercury V-200?
Yes. Verified V-200 applications include serial
0G960500 thru 1B226999.
Does it fit Mercury V-135?
Yes. Verified V-135 fitment is
0G960500 thru 0T178499.
Does it fit a Mercury 140 Jet?
Yes. Verified 140 Jet applications are
0G960500 thru 0T178499.
Should I verify my serial number before ordering?
Yes. Mercury used different electrical components across similar engine
families, so the serial number should always be verified.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 continental U.S.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1-5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Parts must be new, unused, and in original packaging.
- Installed electrical parts are not returnable.
- Return authorization is required before sending items back.
Need help verifying fitment?
Contact Pro Marine
Phone: 941-721-3000
Searchable Terms
18-99253, Sierra 18-99253, 144-7185, 857185T1, Mercury 857185T1, Mercury control module, Mercury ignition control module, Mercury V135 control module, Mercury V140 control module, Mercury V150 control module, Mercury V200 control module, Mercury XR6 control module, Mercury XR-6 module, Mercury Magnum III module, Mercury 140 Jet control module, discontinued Mercury control module, Mercury 857185 replacement, Sierra Mercury control module, 0G960500, 0T178499, 0T178500, 1B226999
857185T1
827509A1
827509A10
827509A4
827509A7
827509A9
827509T7
821889A29
821889A40
821889A42
821889A50
821889A51
821889A20
821889A29
821889A30
821889A36
821889A40
821889A44
821889A51
821889A52
821889A6
821889A29
821889A40
821889A51
821889A55
857169T2
8300467
822779A12
822779A13
822779A14
822779A2
827509A12
827509A6
OEM Mercury CDI Ignition Module
Mercury 8HP-15HP FourStroke CDI Unit 835401T1
This genuine OEM Mercury CDI ignition module is used on select Mercury 8HP, 9.9HP, 13.5HP, and 15HP 4-stroke outboards.
The CDI unit controls ignition timing and spark output for compatible carbureted Mercury small FourStroke engines. It replaces Mercury OEM numbers 835401, 8354011, and 835401T1.
Compatible Applications
| Engine Model | Engine Type | Serial Range | Application Notes |
|---|---|---|---|
| Mercury 8HP | 4-Stroke Carbureted | 0P086824 THRU 0P400999 | Bodensee / international applications |
| Mercury 9.9HP | 4-Stroke Carbureted 323cc | 0G760300 THRU 1B226999 | Select 9.9HP FourStroke models |
| Mercury 9.9HP | 4-Stroke Carbureted 323cc | 0P075166 THRU 0P400999 | Select 9.9HP FourStroke models |
| Mercury 13.5HP | 4-Stroke Carbureted | 0P134638 THRU 0P400999 | International applications |
| Mercury 13.5HP | 4-Stroke Carbureted | 0P401000 & Up | International applications |
| Mercury 15HP | 4-Stroke Carbureted 2-Cylinder | 0G760300 THRU 1B226999 | Select 15HP FourStroke models |
| Mercury 15HP | 4-Stroke Carbureted 2-Cylinder | 0P075166 THRU 0P400999 | Select 15HP FourStroke models |
| Mercury 15HP | 4-Stroke Carbureted 2-Cylinder | 1B227000 THRU 1B727495 | Select 15HP FourStroke models |
| Mercury 15HP | 4-Stroke Carbureted 2-Cylinder | 0P401000 & Up | Select 15HP FourStroke models |
OEM Part Numbers & Supersessions
| Type | Part Number |
|---|---|
| Current Mercury OEM Number | 835401T1 |
| Mercury Cross Reference | 835401 |
| Superseded Mercury OEM Number | 8354011 |
What This CDI Ignition Module is Used For
This Mercury CDI ignition module is part of the outboard ignition system. It helps control spark timing and ignition output so the engine can start, idle, accelerate, and run properly.
A failing CDI module may cause weak spark, intermittent spark, hard starting, misfiring, poor running, or no-start conditions.
CDI modules are commonly replaced during ignition troubleshooting after confirming related components such as spark plugs, ignition coils, kill switch wiring, stator output, and grounds are operating properly.
Using the correct OEM Mercury module helps maintain the proper ignition characteristics for compatible small Mercury FourStroke outboards.
Key Features and Benefits
- Genuine OEM Mercury CDI ignition module
- Fits select Mercury 8HP, 9.9HP, 13.5HP, and 15HP 4-stroke outboards
- Designed for compatible carbureted 2-cylinder Mercury FourStroke engines
- Controls ignition spark output and timing
- Direct replacement for Mercury 835401T1
- Replaces Mercury 835401 and superseded 8354011
- Common replacement during ignition system troubleshooting
- OEM Mercury fit and electrical compatibility
CDI Ignition Module Details
- Brand: Mercury Marine
- Part Type: CDI Ignition Module / CDI Unit
- Current OEM Number: 835401T1
- Cross Reference Numbers: 835401, 8354011
- Application: Mercury 8HP-15HP 4-Stroke Outboards
- System: Electrical / Ignition System
- Engine Type: Carbureted FourStroke
- Approximate Model Years: 1995-2006 models where applicable
FAQ
What engines does this CDI module fit?
This module fits select Mercury 8HP, 9.9HP, 13.5HP, and 15HP carbureted 4-stroke outboards depending on serial number range.
Is this an OEM Mercury part?
Yes. This is listed as an OEM Mercury CDI ignition module with manufacturer item number 835401T1.
Does this replace Mercury 8354011?
Yes. Mercury part number 8354011 has been superseded to 835401T1.
What are symptoms of a bad CDI module?
Common symptoms may include no spark, weak or intermittent spark, hard starting, misfiring, poor running, or no-start conditions.
Should I verify my serial number before ordering?
Yes. Mercury used different ignition components across similar horsepower models, so the engine serial number should always be checked before ordering electrical parts.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 (continental U.S.).
- Orders ship via UPS, USPS, and FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1–5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Electrical parts should be installed only after diagnosis confirms the correct failure point.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Terms
835401T1, 835401, 8354011, Mercury CDI ignition module, Mercury CDI unit, Mercury ignition control module, Mercury 8HP CDI module, Mercury 9.9HP CDI module, Mercury 13.5HP CDI module, Mercury 15HP CDI module, Mercury 4 stroke CDI, Mercury 323cc CDI, Mercury 15HP carb CDI, Mercury electrical ignition module, Mercury FourStroke no spark, Mercury outboard ignition parts
835401T1
8354011
11737M
11737T
18-5136
6F5-85540-21-00
6F5-85540-22-00
6F5-85540-23-00
CDI Unit 9369585540P
The 9369585540P CDI Unit is a replacement ignition module used on Yamaha and Mercury 2-cylinder 2-stroke outboards. This unit controls ignition timing and spark delivery, ensuring reliable starting and smooth engine performance.
Fitment Overview
This CDI unit replaces multiple Yamaha and Mercury ignition modules, including 695-85540-10-00, 695-85540-11-00, 695-85540-12-00, 43077M, and 43077T. These part numbers are used across small horsepower 2-cylinder outboards.
Compatibility
| Brand | Horsepower | Engine Type |
|---|---|---|
| Yamaha | 9.9 HP | 2-Cylinder 2-Stroke |
| Yamaha | 15 HP | 2-Cylinder 2-Stroke |
| Yamaha | 25 HP | 2-Cylinder 2-Stroke |
| Mercury / Mariner | 9.9 HP | 2-Cylinder 2-Stroke |
| Mercury / Mariner | 15 HP | 2-Cylinder 2-Stroke |
| Mercury / Mariner | 20 HP | 2-Cylinder 2-Stroke |
| Mercury / Mariner | 25 HP | 2-Cylinder 2-Stroke |
This ignition module is used across multiple model years depending on ignition system configuration. Always confirm using your original CDI number or engine diagram.
Fits These Serial Ranges
This CDI unit does not follow a single serial break and is used across multiple Yamaha and Mercury 2-cylinder ignition systems.
Important: Match your existing CDI number to one of the cross references below to confirm correct fitment.
Part Numbers and Cross References
| Type | Part Number |
|---|---|
| Pro Marine | 9369585540P |
| Yamaha OEM | 695-85540-10-00 |
| Yamaha OEM | 695-85540-11-00 |
| Yamaha OEM | 695-85540-12-00 |
| CDI Electronics | 117-695-11 |
| CDI Electronics | 17-69511 |
| Sierra | 18-5131 |
| Mercury OEM | 43077M |
| Mercury OEM | 43077T |
| Mercury OEM | 69450M |
What This Part Is Used For
The CDI (Capacitor Discharge Ignition) unit stores and releases electrical energy to fire the spark plugs at the correct time. It is a critical component in the ignition system for proper engine operation.
- Controls ignition timing
- Delivers spark to ignition coils
- Ensures reliable starting
- Supports smooth engine performance
A faulty CDI unit can cause no spark, intermittent spark, misfires, or engine shutdown.
FAQ
What engines does this CDI fit?
It fits Yamaha and Mercury 2-cylinder 2-stroke outboards in the 9.9HP to 25HP range.
How do I confirm fitment?
Match your existing CDI part number to one of the cross references listed above.
Is this a Mercury switch box?
Yes, this unit replaces Mercury switch box numbers such as 43077M and 43077T.
What are signs of a bad CDI?
No spark, weak spark, intermittent misfire, or engine not starting.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 (continental U.S.).
- Orders ship via UPS, USPS, and FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1–5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Part Numbers
9369585540P, 695-85540-10-00, 695-85540-11-00, 695-85540-12-00, 117-695-11, 17-69511, 18-5131, 43077M, 43077T, 69450M
17-69511
18-5131
43077M
43077T
69450M
695-85540-10-00
695-85540-11-00
695-85540-12-00