OTC
3631 logic probe tester
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Find on AmazonModel: 3631
The logic probe itself, with its 12-foot twin-clip coil cord lead.
Important limit: Tops out at 26 V, so it is not for anything above 24-volt systems
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Compare versions and packagesSpecifications checked November 5, 2026. Full product details
OTC 3631 Heavy-Duty Logic Probe Tester
A 3-26 V high-impedance automotive logic probe with red and green LEDs that show ground, power and pulse signals, for testing injectors, solenoids and sensors on 6-, 12- and 24-volt systems.
Selected package: 3631 logic probe tester.
Model: 3631
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| Testing range | 3 to 26 volts |
|---|---|
| Voltage systems | 6-, 12- and 24-volt systems (per the maker's brochure) |
| Input | High impedance input, compatible with computer circuits and sensors |
| Indicators | Bright red and green LEDs interpret voltage signals such as ground, power and frequency |
| What it tests | Fuel injectors, solenoids, presence of serial data, tach reference signals; output tests on MAF, cam, crank, Hall Effect and VRS sensors |
| Air bag safe | Yes (per the maker's list of features) |
| Leads | 12-foot heavy-duty twin-clip red coil cord lead (per the maker's brochure; the product page calls it a heavy-duty twin clip red coil cord lead) |
| Probe | Heavy-duty stainless steel probe with insulated shaft |
| Handle | Ergonomic, slim clear handle with positive contact molded strain relief |
| Power | Powered by the circuit under test; no batteries |
| Product dimensions | 2.20 x 13.60 x 2.00 in (maker's product page) |
From manufacturer documentation, checked November 5, 2026. Spotted an error? Tell us.
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The Power Probe 3 platform with an added resistance measurement mode: it supplies 12/24 V power or ground at the probe tip, reads DC voltage and polarity, checks continuity and measures resistance from 0 Ω to 25 kΩ, all in one tool with a 20 ft cable.
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A 12-24 V automotive circuit tester kit that combines the Power Probe 3 digital voltmeter and continuity tester with extended-reach accessories, including a 20 ft cable extension, cigarette lighter adapter, auxiliary ground lead and a protective carrying case.
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