Honda Accord 1990–1993 TCM

Post-Repair Troubleshooting Guide

(Use this only if issues remain after UpFix TCM service.)

Step 1 – Confirm the Current Symptoms

Verify whether the vehicle is still experiencing:

• Harsh or erratic shifting

• Stuck in one gear (failsafe/limp mode)

• Torque converter lock-up not engaging

• Intermittent or heat-related transmission behavior

Document whether the issue is constant or intermittent and whether it occurs only after the vehicle warms up.

Step 2 – Recheck for OBD-I Transmission Codes

Retrieve transmission codes using the service connector under the dash.

Common codes that may still appear:

• Code 3 / 9 – Torque converter lock-up

• Code 7 / 8 – Shift solenoid A or B

• Code 14 – Linear solenoid

• Code 16 – Solenoid circuit or control issue

If the same code returns immediately after repair, the fault is often external to the TCM.

Step 3 – Verify Power, Grounds, and Vehicle Inputs

Most post-repair issues are caused by conditions outside the TCM.

Check the following:

• Battery voltage and charging system stability

• All transmission-related fuses test good

• TCM connectors are fully seated with no corrosion or bent pins

• Main engine and body grounds are clean and tight

• Throttle Position Sensor (TPS) signal is smooth with no dropouts

Voltage instability or poor grounds can cause false transmission codes even with a good TCM.

Step 4 – Inspect External Transmission Components

If codes persist, inspect components controlled by the TCM:

• Measure shift and lock-up solenoid resistance at the transmission

• Inspect transmission wiring for damage, oil intrusion, or poor repairs

• Check for aftermarket wiring, alarms, or remote-start systems tied into the transmission or TPS circuits

Multiple solenoid codes are often caused by wiring or power issues, not a failed module.

Step 5 – Understand the Scope of the Repair

The TCM refurbishment corrects known internal failures caused by aging capacitors and circuit damage.

If symptoms remain after repair, the root cause is typically:

• A failed solenoid

• Wiring or connector issues

• Sensor signal problems

• Power or ground instability

• Mechanical transmission faults

Opening or tampering with the TCM after repair may void the warranty.

Step 6 – Next Steps if Issues Continue

If all external checks pass and problems persist:

• Stop further testing that involves the TCM itself

• Contact UpFix support with the symptoms and any stored codes

• We may recommend additional vehicle-side diagnostics or a warranty evaluation if appropriate