Volvo Penta Ignition Control Module 3858984
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Volvo Penta OEM Ignition Control Module – Part No. 3858984
| Part Number | 3858984 |
| Brand | Volvo Penta |
| Component Type | Ignition Control Module |
| Ignition System | Delco HVS / MPI / GXi-era distributor ignition |
| Installed With | Ignition Coil 3861985 and Cooling Plate 3858985 |
| Related Hardware | Bolt 3858986 · Bracket 3863294 |
| Weight | Approx. 40 g |
| Supersedes | No confirmed OEM superseding number — 3858984 is the current active number |
| Replaced By | No documented replacement |
| Aftermarket Cross-References | Sierra 18-5117 · Mallory 9-29807 · M-1599 / M1599 · REC3858984 |
Note: 3858984 is the later Delco HVS-era module. Do not confuse with 3854003, which is an earlier Delco EST-type module used on older Volvo Penta gasoline engines. Both appear on GM-based engines — confirm by ignition diagram and engine serial number.
Compatible Applications
Volvo Penta used different ignition modules across similar GM-based gasoline engines. Confirm the exact engine model, suffix, serial number, and existing module part number before ordering. Do not order by displacement alone.
- Volvo Penta 4.3GXi / 4.3GXiE / 4.3OSi
- Volvo Penta 5.0GXi / 5.0GXiC / 5.0GXiCE / 5.0GXiE / 5.0OSi (including -B, -BF suffixes)
- Volvo Penta 5.7Gi / 5.7GiE / 5.7GiC / 5.7GiCE (including -B, -BF, -C suffixes)
- Volvo Penta 5.7GXi / 5.7GXiE / 5.7GXiC / 5.7GXiCE (including -C, -CF suffixes)
- Volvo Penta 5.7OSi / 5.7OSXi (including -A, -AF suffixes)
- Volvo Penta V6-200 / V6-225
- Volvo Penta V8-225 / V8-270 / V8-300 / V8-320
Symptoms of a Failing Ignition Control Module
Diagnose the ignition system thoroughly before replacing the module — coil, cap, rotor, wiring, and power/ground faults can produce identical symptoms. Common indicators of module failure include:
- Complete loss of spark with no-start condition
- Intermittent spark loss or heat-related ignition dropout
- Engine stalling that worsens as the engine heats up
- Misfire under load with no cap, rotor, or coil fault
- Module-related ignition diagnostic fault codes
- Physical damage to the module housing or connector
Installation Notes
The module is mounted with cooling plate 3858985 and installed alongside ignition coil 3861985, bolt 3858986, and bracket 3863294 in the ignition assembly. Proper heat transfer through the cooling plate mounting surface is important for module reliability — ensure the mounting area is clean and the assembly is torqued per the Volvo Penta service procedure. Inspect the electrical connectors, coil, and surrounding ignition wiring at the same time.
Related Parts
- Volvo Penta Ignition Coil 3861985 — installed with this module
- Volvo Penta Cooling Plate 3858985 — module mounting plate
- Volvo Penta Distributor Cap 3858975 — related HVS ignition component
- Volvo Penta Distributor Rotor 3858977 — related HVS ignition component
Technical FAQ
What is the difference between 3858984 and 3854003?
3854003 is an earlier Delco EST-type ignition module used on older Volvo Penta gasoline engines. 3858984 is the later Delco HVS / MPI-era module. Both can appear on GM-based Volvo Penta engines of similar displacement — the ignition diagram and engine serial number are the correct way to identify which module your engine uses.
Does the cooling plate need to be replaced at the same time?
Not necessarily, but inspect it. The cooling plate 3858985 ensures proper heat dissipation from the module. If it is corroded, warped, or has poor surface contact, replacing it at the same time avoids heat-related module failure after service.
Can I diagnose the module before replacing it?
Yes — and it’s recommended at $439. Before ordering, verify the ignition coil, cap, rotor, power supply, ground, and distributor wiring are all serviceable. Heat-soak testing (symptom appears when warm, clears when cold) is a classic indicator of module failure specifically.
Are Sierra 18-5117 and Mallory 9-29807 direct replacements?
They are listed as aftermarket cross-references for this application. Verify the cross-reference against the exact engine model and ignition-system version before use, as module specifications can be sensitive to ignition-system generation.
Parts Desk Insights
This module is almost always ordered after the coil, cap, and rotor have already been ruled out — it’s the last ignition component customers replace when chasing a heat-related no-start or stall. The most common ordering mistake is confusing it with the older 3854003 EST module, which can show up on nearby engine models. Confirming the ignition diagram and module number before ordering is faster than a return. At this price point, pairing the order with the cooling plate is worth mentioning — a failed heat-transfer surface is a common cause of repeat module failure.
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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