Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the computer that controls the car's transmission found a mistake in its memory check. It's like when your game console finds a problem with a game save file.
The Transmission Control Module (TCM) performs a checksum test to verify the integrity of its stored data. A checksum error indicates a mismatch, suggesting potential data corruption.
The TCM uses a checksum algorithm to validate the integrity of its firmware and data. If the calculated checksum does not match the expected value, it triggers the P1699 code, indicating potential memory corruption or a malfunction within the TCM.
• Check Engine Light is on
• Transmission may not shift properly
• Vehicle may go into limp mode
• Faulty Transmission Control Module
• Corrupted firmware or software in the TCM
• Electrical issues such as poor connections or damaged wiring
TCM: Transmission Control Module
Checksum: A method of checking data integrity
• Use an OBD-II scanner to confirm the P1699 code.
• Inspect the TCM for any signs of physical damage.
• Check wiring and connections to the TCM for corrosion or damage.
• Reprogram or update the TCM software.
• Repair or replace damaged wiring or connectors.
• Replace the TCM if it is found to be faulty.
• OBD-II Scanner
• Multimeter
• Screwdriver set
$300 - $1,200
Moderate
• Dodge Caravan
• Chrysler Town & Country
• Jeep Grand Cherokee
• Regularly update vehicle software.
• Ensure all electrical connections are secure and free of corrosion.
• Avoid exposure to extreme temperatures.
Transmission Control
• Avoid driving the vehicle if it is in limp mode.
• Consult a professional mechanic for diagnosis and repair.
Check with the vehicle manufacturer for warranty coverage on the TCM.
This code has been more common in older vehicles with early TCM technology.
Moderate – It should be addressed soon to prevent potential transmission issues.
Driving with a malfunctioning TCM can lead to unsafe driving conditions. Ensure repairs are performed by a qualified technician.
• Vehicle must be running.
• TCM must be powered and communicating with the vehicle's network.
The TCM is usually located near the transmission or within the engine compartment.
Q: Can I drive with a P1699 code?
A: It's not recommended as it may lead to transmission issues. Have it checked by a mechanic.
Q: How is a checksum error fixed?
A: It can often be resolved by reprogramming the TCM or fixing any wiring issues.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.