Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P1698: No Bus Message From Trans Control Module: Testing
- Turn the ignition on. With the DRBIII(R), erase DTCs. Cycle the ignition key off and on several times, leaving the ignition on for at least 20 seconds each time. Turn the ignition on. With the DRBIII(R), read DTCs. Does the DTC reset? If yes, go to next step. If no, go to step 3 .
- With the DRBIII(R), attempt to communicate with the TCM. Can communication be established with the TCM? If yes, replace PCM. If no, perform the appropriate symptom-related test. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
- Conditions that set DTC are not present at this time. The following list may help in identifying the intermittent condition:
- With the engine running at normal operating temperature, monitor the DRBIII(R) parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set.
- Review the DRBIII(R) Freeze Frame information to identify under what conditions the DTC set.
- Refer to any Technical Service Bulletin (TSB) that may apply.
- Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.
- Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
Were any of the above conditions present? If yes, repair as necessary. If no, test is complete.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.