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A small relay can create a large diagnostic mess when the replacement is chosen by shape alone. The housing may look familiar, but a buyer still needs to confirm the part number, pin count, contact rating, coil suppression, and whether the mounting style matches the vehicle or equipment.

Bosch 0986332402 is a useful example because it is a 5-pin, 12 V changeover mini relay with a diode. It also appears in Bosch relay data as the successor reference for 0332209158, making it a practical part-number match question rather than a generic relay-shopping decision.

What Parts Universe lists

Parts Universe currently lists this item as BOSCH 0986332402 Changeover Mini Relay, Diode, 5 Pins, 12 V, 20/30 A. The active Shopify product record verified for this article shows:

• Parts Universe SKU: BSH-0986332402
• UPC: 4047024887020
• Current Parts Universe price: $5.99
• Current inventory: 202 units
• Current inventory policy: CONTINUE
• Current status: active and available for sale

What Bosch verifies

Bosch I-Business describes Bosch relays as a range of 12 V and 24 V relays for mobile and stationary applications. In Bosch's mini-relay table, part number 0986332402 is listed with predecessor 0332209158, current rating 30/20 A, 5 pins, diode coil connection, a mounting bracket, and 150,000 lifetime cycles.

Bosch Mobility Aftermarket also frames mini relays around vehicle electrical jobs such as fuel pumps, direction indicators, horns, all-round beacons, and headlights. That application list is a category guide, not a fitment promise for every vehicle.

When this relay is a good candidate

• The original relay or service information calls for Bosch 0986332402.
• The old relay is marked 0332209158 and Bosch replacement data points to 0986332402.
• You need a 5-pin 12 V changeover mini relay with diode coil suppression, not a 4-pin normally-open relay or a relay with different coil protection.
• The socket, terminal layout, and mounting bracket match the relay location you are servicing.

What to check before ordering

Do not use amperage and pin count as the only decision. For relay replacement, check the relay diagram on the case, the terminal numbers, the service manual, and the connector cavity. A diode relay can be polarity-sensitive, so installing a different coil-suppression style can create diagnostic faults or circuit damage.

If the old relay is stuck, Bosch's relay-change guidance says to disconnect the battery to prevent discharge and short circuits, then carefully loosen the relay. Bosch also recommends a function test by cross-swapping with an identical relay. Identical is the important word: cross-swap only when the rating, pin layout, and relay function match.

How this differs from a 100A power relay

Parts Universe recently covered Bosch 0332002159, a 100A normally-open power relay. Bosch 0986332402 is a different buyer problem: it is a compact 5-pin changeover mini relay rated 30/20 A with diode suppression. Do not substitute between those categories just because both are Bosch relays.

Practical safety notes

• Disconnect the battery before relay removal when the service procedure calls for it.
• Do not bypass a relay socket with wire or tools to "test" a circuit unless the service information explicitly supports that method.
• If a replacement relay fails immediately, find the short circuit, overload, water intrusion, or terminal damage before installing another relay.
• Keep relay replacement within the vehicle manufacturer's service information and warranty requirements.

Related Parts Universe links

• Shop Bosch 0986332402 changeover mini relay
• View Bosch 0332209158 relay reference
• Browse relays and flashers
• Browse electrical and electronics
• Browse sensors, relays, and electrical
• Browse fuses and accessories

For buyers, the main takeaway is simple: Bosch 0986332402 is not just "a 5-pin relay." It is the documented Bosch successor path for 0332209158 with a diode coil connection and 30/20 A changeover-mini-relay specs, so match those details before buying or swapping.

A relay is easy to overlook because it is usually small, inexpensive, and hidden in a fuse box or auxiliary bracket. But on a high-current circuit, replacing it by shape alone is a gamble. The buyer-friendly question is simple: does the replacement match the circuit's current demand, pin layout, coil protection, mounting style, and service information?

Bosch 0332002159 is a power relay Parts Universe carries for shoppers who need a 12 V, 100 A, normally-open relay. Bosch's relay catalog places part number 0332002159 in its 12 V normally-open power-relay section and lists it as a 4-pin, resistor-coil relay with a mounting bracket and 100,000-cycle lifetime entry.

What Parts Universe lists

Parts Universe currently lists this item as Bosch 0332002159 Normal Open Power Relays, 12 V, 100 A, 4 Contacts, Resistor. The active Shopify product record verified for this article shows:

• Parts Universe SKU: BSH-0332002159
• Manufacturer part number: 0332002159
• Barcode: 03165141212778
• Current Parts Universe price: $32.99
• Current inventory: 92 units
• Current status: active and available for sale

What Bosch verifies

Bosch separates relay families by job size. Its public relay information describes power relays as products used for switching operations in engines, starters, and other large consumers. In Bosch's relay catalog table, 0332002159 appears under 12 V NO power relays with these key attributes:

• Product family: power relay
• Part number: 0332002159
• Current: 100 A
• Number of pins: 4
• Coil connection: resistor
• Mounting bracket: yes
• Catalog lifetime entry: 100,000 cycles

When a 100A power relay makes sense

This is the kind of relay to consider when the original circuit was designed around a high-current power relay, not a small micro relay or generic accessory relay. Typical buyer situations include replacing a missing or failed relay where the original part number, service manual, or relay markings call for the same Bosch number or matching electrical specification.

Do not upgrade to a higher-current relay as a shortcut for a wiring problem. A 100 A rating only helps when the rest of the circuit is designed for that load: wire gauge, fuse protection, connectors, terminals, mounting, heat, and duty cycle all still matter.

Five checks before ordering

1. Match the part number first. If the removed relay is Bosch 0332002159, this listing is the direct product to review. If it is a different number, confirm a documented cross-reference before substituting.
2. Confirm 12 V normally-open operation. A normally-open relay behaves differently from a changeover relay, latching relay, or normally-closed relay.
3. Count the pins and compare the diagram. Four pins are not enough by themselves; terminal numbers and the circuit diagram must also match.
4. Check coil protection. Bosch lists this part with a resistor coil connection. Do not swap resistor and diode-protected relays casually in electronically controlled circuits.
5. Check mounting. Bosch lists a mounting bracket for this part. That matters when the relay is secured near vibration, heat, or service access points.

Safety notes for relay replacement

• Disconnect the battery when the service procedure calls for it; Bosch's relay-change guidance specifically warns about preventing discharge and short circuits.
• Do not bypass a relay socket with wire or tools to "see what happens" on a high-current circuit.
• Inspect terminals for heat discoloration, looseness, corrosion, or melted plastic before installing the new relay.
• Replace damaged sockets or terminals instead of relying on the relay to mask poor contact.
• If the fuse opens again after relay replacement, diagnose the load and wiring before installing another relay.

Good fit, bad fit

Good fit: your service information or original relay calls for Bosch 0332002159, a 12 V normally-open 100 A power relay with 4 pins, resistor coil protection, and a mounting bracket.

Bad fit: you only know the relay is black, square, or has four terminals. Relay housings can look similar while the internal circuit, coil protection, and current rating are different.

Related Parts Universe links

• Shop Bosch 0332002159 12 V 100 A power relay
• Browse relays and flashers
• Browse electrical and electronics
• Browse sensors, relays, and electrical
• Browse fuses and accessories

Bosch 0332002159 is a practical choice when the spec sheet, original relay, and circuit design all point to the same high-current relay. Match the number, verify the circuit, and treat any heat-damaged socket as part of the repair instead of an unrelated detail.

Bosch invented the automotive relay in 1956 and remains the gold standard for OEM and aftermarket applications worldwide. Whether you're replacing a failed relay or building a custom electrical system, here's everything you need to know.

What Is an Automotive Relay and Why Does It Matter?

A relay is an electrically-operated switch. It allows a small current (from a switch, fuse box, or control module) to control a much larger current (to a motor, compressor, fan, or lighting circuit). Without relays, every high-current circuit would need heavy-gauge wiring all the way to the dashboard switch - impractical and dangerous.

Relays also protect switches and control modules from high-current damage. Your AC compressor, cooling fan, fuel pump, starter, and horn all use relays.

Bosch Relay Types

Mini Relay (Most Common - 12V, 30A/40A)

The standard ISO mini relay used in virtually every modern vehicle fuse box. Fits the universal 5-pin relay socket. Available in normally open (NO) and change-over (CO) configurations.

• Bosch 0332019150 - 12V, 30A, normally open (4-pin)
• Bosch 0332019151 - 12V, 40A, normally open (4-pin)
• Bosch 0332014456 - 12V, 30A/40A, change-over (5-pin)

Best for: direct replacement in any modern vehicle fuse box, lighting circuits, accessory wiring

Normal Open Power Relay (Heavy Duty)

For high-current applications requiring more than 40A. Used in cooling fans, starter circuits, and high-draw accessories.

• Bosch 0332002156 - 12V, 75A, normally open. One of the most popular heavy-duty relays for aftermarket applications.

Best for: electric cooling fans, winches, high-power lighting (LED light bars), compressors

Time Delay Relay

Adds a programmable delay before opening or closing. Used in glow plug circuits (diesel engines), turbo timer applications, and HVAC systems.

Flasher Relay

Controls turn signal and hazard light timing. Electronic flashers (replacing old thermal flashers) are required when upgrading to LED turn signals to maintain correct flash rate.

How to Read a Bosch Relay Part Number

Bosch relay part numbers follow a consistent format:

• 0 332 - Product family (relays)
• 002/019/014 - Sub-series (power/mini/change-over)
• Last 3 digits - Specific variant (voltage, amperage, contact configuration)

5-Pin vs 4-Pin Relays: What's the Difference?

4-pin relays are normally open (NO) - the circuit is open at rest and closes when the relay energizes. Used for most on/off applications.

5-pin relays are change-over (CO) - they have both a normally open AND a normally closed contact. When de-energized, the NC contact is connected. When energized, the NO contact connects. Used when you need to switch between two circuits.

Pin numbering is standardized:

• Pin 85 & 86: Coil terminals (12V control signal)
• Pin 30: Power input (battery/fused power)
• Pin 87: Normally open output (connects when energized)
• Pin 87a: Normally closed output (5-pin relays only)

How to Test a Bosch Relay

1. Remove the relay from its socket.
2. Use a multimeter set to continuity/resistance. Test between pins 85 and 86 - you should read 70-90 ohms (coil resistance). Open circuit = failed coil.
3. Apply 12V to pins 85 and 86. Test continuity between pins 30 and 87 - you should now read continuity. No click or continuity = failed contacts.
4. Remove power - continuity between 30 and 87 should disappear.

Common Relay Failures and Symptoms

• No click when energized: Failed coil - replace the relay
• Click but no output: Burned contacts - replace the relay
• Relay stuck on (won't de-energize): Welded contacts from current overload - replace relay and check for short circuit
• Intermittent operation: Corroded contacts or loose socket - clean socket terminals or replace relay

Shop Bosch Relays

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