Why does my Toyota T100 automatic slip or set code P0770?

Short answer: First, not everything is a problem: older Toyotas, including the T100, hold lower gears for the first few shifts on a cold start to warm the engine faster, and one owner of a T100 says theirs does this noticeably. True slipping (revs flare without the truck moving faster) is different and needs a fluid check soon. If the check engine light shows P0770, that's shift solenoid E, which sits inside the transmission. One owner's mechanic flushed the fluid and replaced a solenoid and filter, but the light kept returning.

Symptom: On the first start of the day it seems to slip or stay in low gears, or the check engine light comes and goes with P0770 on a high-mileage truck.

What to check first

1. Tell the difference: holding low gears briefly when cold can be normal; engine revs flaring without speed increase is slipping.
2. Check fluid level and condition. Low, dark or burnt fluid needs attention.
3. Check for a delay going from Reverse to Drive.
4. If P0770 is set, have a transmission shop test the solenoid circuit and wiring before replacing parts. See our P0770 page.

Likely causes

1. Normal cold-shift programming. Holds low gears briefly when cold.
2. Shift solenoid E or its wiring (P0770). Internal to the transmission.
3. Worn transmission or old fluid. Slipping when cold can be an early warning.

What it usually costs

No dollar figures were posted. The P0770 owner's mechanic had already done a fluid flush plus a solenoid and filter without curing the light, so ask a transmission shop for a diagnosis before more parts.

Is it safe to keep driving?

If it's only the brief cold-shift behavior, yes. Real slipping or a flashing light means get it checked soon; don't tow heavy loads. Verify with a mechanic.

DIY or shop?

DIY for fluid checks. Solenoid diagnosis and replacement are transmission-shop work for most owners.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists no recall for automatic transmission problems on the Toyota T100 for these model years (checked 2026-10-25). Other recalls may exist for your car, so check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• NHTSA complaints: 50 keyword-matched complaints for Toyota T100 1993–1998 (of 338 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-25; keywords: transmission, shift, slip, gear, reverse, engage, limp, torque converter, shudder, P0770, solenoid). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1996 Toyota T100 - 1st start trans slip on Car Talk, an owner said their T100 slipped on the first start of the day. One member warned cold slipping can signal trouble ahead and to check the fluid; another, who owns a T100 and an Avalon, said older Toyotas hold low gears for the first few shifts to warm up, and it's very noticeable on the T100.
• In Another toyota truck with P0770 code on Car Talk, a 1998 T100 V6 4WD with 169,000 miles kept setting P0770. The mechanic flushed the transmission and replaced a solenoid and the filter, but the light kept coming back. A member said the code means shift solenoid E and the job needs a transmission shop, and another warned that the truck wasn't a good choice for towing another car on a long trip anyway.

Quick tip

Don't panic over the first cold shift or two, but don't ignore real slipping. If P0770 keeps coming back after a solenoid, the wiring or the transmission itself needs a proper diagnosis.

Vehicle focus: 1993–1998 Toyota T100 pickup with the automatic transmission.

Safety / mechanic note

A slipping transmission can lose drive in traffic; avoid heavy towing until checked. Verify with a mechanic.