Tow/Haul Light Flashing: What It Means and How To Fix It

Your tow/haul light is flashing on the dash. The TCM is telling you something is wrong with the transmission. Heres what causes it and how to fix it before damage gets worse.

What the flashing tow/haul light means

TCM has detected a fault:

Why it flashes:

Common causes

#1: Solenoid pack failure

#2: Internal harness

#3: Speed sensor

#4: TEHCM (6L80/8L90)

#5: Burnt fluid

What to do immediately

Step 1: Pull DTCs

Step 2: Check fluid

Step 3: Try reset

Step 4: Avoid heavy load

Cost by cause

Cheap fixes ($30-$300):

Mid-tier ($700-$1,500):

Expensive ($1,500-$2,500):

Major ($3,000+):

By trans family

4L60E (rare flashing tow/haul):

4L80E flashing:

6L80 flashing:

Allison 1000 flashing:

Can you keep driving?

Light load, short distance:

Highway speeds:

With trailer attached:

Reset attempts

Battery disconnect:

Drive cycle:

Scan tool clear codes:

Cant just reset without fixing

Wont resolve:

May resolve:

Tuned truck flashing

Common cause:

Fix:

Service intervals to prevent

Stock daily:

Tow use:

Tuned:

Questions to ask shop

Before $1,500+ repair:

If shop wants major repair without diagnosis: get second opinion

When to consider rebuild

Rebuild likely needed if:

Service NOT rebuild if:

Pre-purchase used truck flashing

If light flashes on test drive:

Sometimes seller has cleared codes:

Insurance / warranty

Extended warranty:

Document:

Bottom line

Most flashing tow/haul lights are:

Cheapest path:

Need solenoid pack, sensors, TEHCM, or rebuild parts? Visit our main catalog. OEM solenoids, harnesses, complete rebuild kits. Free shipping over $70.

Related:

• Stuck in 3rd / limp mode
• 6L80 solenoid pack
• Allison limp mode