This is one of the easiest jobs on a T1 Silverado, with two small catches. The hold-down bolt is a 13 mm at the bottom of the battery, tucked against the fender, so you need a 6-10 inch extension and ideally a wobble to reach it — trying to do it with a short socket is the main reason this turns into a knuckle-busting half hour. Everything else is 10 mm.
The bigger thing people get wrong is the battery type. These trucks run Auto Stop/Start and a battery current sensor on the negative cable, and they expect an AGM battery (usually Group 48/H6). Drop in a bargain flooded battery and you will get short life, Stop/Start acting up, and sometimes charging complaints. Also do the battery sensor reset with a scan tool if you have one; without it the truck keeps charging for the battery it thinks it still has.
| Item | Type | |
|---|---|---|
| Safety glasses Battery acid and sparks at the terminals. | Safety | shop |
| Nitrile gloves Keeps acid residue and corrosion off your hands. | Safety | shop |
| Memory saver OBD-II port or 12V socket type Keeps radio presets, HVAC, window/seat memory and learned data alive while the battery is out. | Recommended | shop |
| Ratchet 3/8 in drive, standard and stubby handy Drives the terminal and hold-down fasteners. | Required | shop |
| Socket 10 mm 6-point, 3/8 in drive Loosens the negative and positive cable clamp bolts. | Required | shop |
| Socket 13 mm 6-point, 3/8 in drive Removes the battery hold-down clamp bolt at the base of the battery. | Required | shop |
| Extensions 3/8 in drive, 6 in and 10 in The hold-down bolt is deep beside the battery and unreachable with a bare socket. | Required | shop |
| Universal swivel / wobble extension 3/8 in drive Helps line up on the hold-down bolt past the fender and cable routing. | Recommended | shop |
| Socket 8 mm, 1/4 in drive Some trucks have an 8 mm nut retaining the negative battery current sensor or a cable bracket. | Recommended | shop |
| Trim/panel pry tool Plastic Pops the plastic battery cover and any clipped wire looms without breaking tabs. | Recommended | shop |
| Battery terminal brush Post and clamp type Cleans corrosion off the cable clamps so the new battery makes solid contact. | Required | shop |
| Battery terminal spreader or flat screwdriver Gently opens a clamp that has been squeezed tight on the old post. | Recommended | shop |
| Battery carry strap or lifting handle A Group 48 AGM weighs 45-50 lb and sits down in a tray behind the fender. | Recommended | shop |
| Torque wrench 3/8 in drive, 5-80 ft-lb Terminal clamps strip or crush easily if over-tightened. | Recommended | shop |
| Battery terminal / corrosion cleaner spray Aerosol Neutralizes acid film on the tray and cable ends. | Consumables | shop |
| Terminal protectant grease or felt washers Dielectric/anti-corrosion Applied after tightening to slow future corrosion. | Consumables | shop |
| Replacement battery Group 48 (H6) AGM, ~730-760 CCA typical; verify your truck's group and type on the old label Auto Stop/Start trucks require AGM; flooded replacements cause premature failure and charging faults. | Parts | shop |
| Scan tool with GM battery replacement reset GDS2/MDI or capable aftermarket (e.g. bidirectional tool) Resets the battery sensor/state-of-health data so the charging system stops targeting an old, worn battery. | Recommended | shop |
Fastener sizes are the same on the 2.7L turbo, 5.3L, 6.2L and 3.0L Duramax — 10 mm terminals, 13 mm hold-down. The difference is count and size: 3.0L Duramax trucks and some dual-battery-optioned gas trucks have two batteries under the hood and should be replaced in matched pairs, while most single-battery trucks use a Group 48 (H6) AGM. A few configurations use a larger group size, so confirm against the label on the battery you pull out.
| Battery cable clamp bolts (10 mm) | about 11 ft-lb (15 Nm) — verify in the service manual |
| Battery hold-down clamp bolt (13 mm) | verify in the service manual |
| Negative current sensor nut (8 mm) | verify in the service manual |
The 10 mm terminal bolts and 13 mm hold-down bolt are correct for T1 Silverado 1500 trucks across all four engines, but battery group size (48/H6 is most common) and the presence of a second battery vary by engine and option code — check the label on your old battery before buying.
Under the hood in the front corner of the engine bay, beneath a snap-on plastic cover. Trucks with the dual-battery setup (3.0L Duramax and some optioned gas trucks) have a second battery in the opposite front corner.
Yes on any truck with Auto Stop/Start, which is nearly all of them. The factory fitment is typically a Group 48/H6 AGM, and switching to a flooded battery usually leads to short life and Stop/Start or charging complaints.
There is no BMW-style mandatory coding, but GM does have a battery replacement/state-of-health reset in the BCM. Running it with GDS2 or a capable bidirectional scan tool makes the charging strategy treat the battery as new; without it, Stop/Start may stay off longer than normal.
A 10 mm socket for both cable clamp bolts and a 13 mm socket for the hold-down clamp bolt, plus a 6-10 inch 3/8 in extension to reach the hold-down. An 8 mm is handy if a cable bracket or the negative current sensor nut is in the way.