The 2003 Isuzu NPR has 12 electrical switch & relay parts with verified fitment on this page — 4 part types and 7 brands, covering both the 4.8L L4 DIESEL Turbocharged and the 5.7L V8. Each part includes a manufacturer part number and application notes.
On the 2003 Isuzu NPR, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches. 10 parts of the 12 listed are A/C Trinary Switch (5 parts), Oil Pressure Sender / Switch (3 parts) and A/C Refrigerant Pressure Switch (2 parts). The other 1 part type covers the remaining 2 parts.
The 2003 Isuzu NPR was sold with both the 4.8L L4 DIESEL Turbocharged and the 5.7L V8. 9 parts fit every engine; the other 3 are engine-specific. Each part shows which engine(s) it fits.
7 brands supply electrical switch & relay parts for the 2003 Isuzu NPR, led by GPD (3 parts), FOUR SEASONS (2 parts) and UAC (2 parts), plus 4 more brands. Quality grades include Economy and Standard Replacement.
A "Popular" badge means the source catalog flagged the part as frequently chosen for the 2003 Isuzu NPR. 1 part has it: UAC SW4004C (A/C Trinary Switch). Each part number opens a page with every vehicle that part fits.
A/C Refrigerant Pressure Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| FOUR SEASONS Fits: all 2003 NPR engines | 20946 | 🇺🇸 US 🇨🇦 CA | Pressure Switch | View on Amazon |
| ULTRA-POWER Fits: 4.8L L4 DIESEL Turbocharged | 1711482 | 🇺🇸 US 🇨🇦 CA | Air Conditioning SwitchTrinary | View on Amazon |
This table covers the pressure switches on the A/C circuit. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
2 A/C Refrigerant Pressure Switch parts are listed for the 2003 Isuzu NPR, from FOUR SEASONS and ULTRA-POWER. 1 part fits every engine; the other 1 is engine-specific.
Listed part numbers: FOUR SEASONS 20946 and ULTRA-POWER 1711482.
A/C Trinary Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| UAC Popular Fits: all 2003 NPR engines | SW4004C | 🇺🇸 US 🇨🇦 CA | Trinary HPCO CF LPCO | View on Amazon |
| FOUR SEASONS Fits: all 2003 NPR engines | 20969 | 🇺🇸 US 🇨🇦 CA | Pressure Switch | View on Amazon |
| GPD Fits: 4.8L L4 DIESEL Turbocharged | 1711482 | 🇺🇸 US 🇨🇦 CA | Trinary SwitchHP OP 384psi | View on Amazon |
| GPD Fits: 4.8L L4 DIESEL Turbocharged | 1711483 | 🇺🇸 US 🇨🇦 CA | Trinary SwitchHP OP 412psi | View on Amazon |
| UAC Fits: all 2003 NPR engines | SW11276C | 🇺🇸 US 🇨🇦 CA | Trinary Switch | View on Amazon |
This table covers the A/C Trinary switches. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
5 A/C Trinary Switch parts for the 2003 Isuzu NPR come from 3 brands — UAC, GPD and FOUR SEASONS. The "Popular" part is UAC SW4004C. 3 parts fit every engine; the other 2 are engine-specific.
Part numbers include UAC SW4004C, FOUR SEASONS 20969 and GPD 1711482, among others listed above.
Oil Pressure Sender / Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| UNITED MOTOR PRODUCTS Fits: all 2003 NPR engines | OPS172 | 🇺🇸 US 🇨🇦 CA | NPR Base Modelwith Gauge | View on Amazon |
| WALKER PRODUCTS Fits: all 2003 NPR engines | 2561001 | 🇺🇸 US 🇨🇦 CA | NPR Base Model | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GPD Fits: all 2003 NPR engines | 1815274 | 🇺🇸 US 🇨🇦 CA | NPR Base Modelwith Gauge | View on Amazon |
This table covers the senders and switches that report oil pressure to the gauge or lamp. Typical signs include a lamp that stays on, or a gauge that never moves. Confirm power and ground at the connector before replacing the sender or switch.
3 Oil Pressure Sender / Switch parts are listed for the 2003 Isuzu NPR, from UNITED MOTOR PRODUCTS, WALKER PRODUCTS and GPD. All of them fit every engine offered in the 2003 NPR.
In the Economy grade, UNITED MOTOR PRODUCTS and WALKER PRODUCTS supply 2 parts: the catalog's value-priced group. A representative part number is UNITED MOTOR PRODUCTS OPS172.
The Standard Replacement section lists 1 option from GPD — built to original-equipment specification. GPD 1815274 is listed in this group.
Listed part numbers: UNITED MOTOR PRODUCTS OPS172, WALKER PRODUCTS 2561001 and GPD 1815274.
Turn Signal Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| DORMAN Fits: all 2003 NPR engines | 2330904 | 🇺🇸 US 🇨🇦 CA | NPR Base Modelwithout Exhaust Brake | View on Amazon |
| DORMAN Fits: all 2003 NPR engines | 2330906 | 🇺🇸 US 🇨🇦 CA | with Exhaust Brake | View on Amazon |
This table covers the combination / turn-signal switches. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
DORMAN supplies both parts for the 2003 Isuzu NPR. All of them fit every engine offered in the 2003 NPR.
Listed part numbers: DORMAN 2330904 and DORMAN 2330906.
Buying Electrical Switch & Relay Parts for a 2003 Isuzu NPR
On this vehicle, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches.
- Match the engine first. Some electrical switch & relay parts fit every engine; others are engine-specific. Each row shows which engine(s) it fits.
- Read the notes on each row for position, trim and spec qualifiers before you order.
- Where labor overlaps, inspect the connector terminals behind any failed switch — heat damage there will kill the new part too.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: A/C Trinary Switch and Oil Pressure Sender / Switch .
Frequently Asked Questions
How many electrical switch & relay parts fit the 2003 Isuzu NPR?
Our catalog currently lists 12 electrical switch & relay parts for the 2003 Isuzu NPR across 4 subcategories and 7 brands, covering both the 4.8L L4 DIESEL Turbocharged and the 5.7L V8. Each part is matched to the engine(s) it fits.
Do electrical switch & relay parts differ between 2003 Isuzu NPR engines?
Some do. 9 parts fit every engine; the other 3 are engine-specific. Each row (and the filter at the top) shows which. If you're unsure which engine you have, check the emissions label under the hood or the 8th character of your VIN.
What are the signs of electrical switch & relay problems on a 2003 Isuzu NPR?
Common symptoms include accessories that work intermittently, a click without action, or one function dead while its fuse tests fine. If you notice any of these, identify the affected subcategory above and cross-reference the part numbers listed.
What should I replace at the same time?
Where labor overlaps, inspect the connector terminals behind any failed switch — heat damage there will kill the new part too.
What do the market flags (US, CA, MX) on each part mean?
They show the market for which the manufacturer published application data for that part — where the vehicle was first sold, not where the part was made. If your 2003 Isuzu NPR was originally sold in the US, the safest choice is a part marked for the US market.
How do I make sure a part fits my 2003 Isuzu NPR?
First match the engine — each row shows which engine(s) the part fits. Then swap a suspect relay with an identical known-good one from the fuse box before buying — it is the fastest diagnostic there is. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 2003 Isuzu NPR
Electrical Switch & Relay Parts for Other Isuzu NPR Years
Switch vehicle or jump to a subcategory
Manufacturer names, model designations and part numbers are used for identification and fitment reference only. AutoFactsDB is an independent catalog and is not affiliated with, endorsed by, or sponsored by any vehicle manufacturer displayed on this page.