EN

Severity: Moderate Code type: Manufacturer-specific (Jeep)

Jeep P1698 Code: No CCD/J1850 Messages Received From TCM

The engine computer stopped hearing from the transmission computer, often leaving the Jeep stuck in one gear.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
No CCD/J1850 Messages Received From TCM
System
Module Communication · Powertrain
Safe to drive?
With caution
Typical repair cost
$40–$900
DIY difficulty
Moderate

On Jeeps where the automatic transmission has its own control module, the PCM and TCM swap data constantly over Chrysler's CCD or J1850 (PCI) bus: engine speed, throttle, gear state and torque management requests. P1698 is stored in the PCM when it receives no bus messages from the TCM for about 10 seconds. This mostly shows up on late-1990s and early-2000s models such as the Wrangler TJ and Liberty with the 42RLE, WJ Grand Cherokees and some Cherokee XJ. When the TCM is silent it's usually because it lost power or ground, or because it has dropped into its own limp mode; that's why the driver typically notices a transmission stuck in one gear before anything else.

Can I keep driving? The Jeep will usually still move, but often only in one gear with sluggish acceleration and high revs at speed. Drive gently and only as far as needed; don't tow or run highway speeds in limp mode.

How to read P1698

How to read P1698P11263984
  1. P Powertrain
  2. 1 Manufacturer-specific
  3. 6 Computer & outputs
  4. 98 Specific fault

Symptoms

  • Check engine light on
  • Transmission stuck in one gear (often second) or no overdrive
  • Harsh engagement into drive or reverse
  • Speedometer or cruise control acting up on some models
  • Problem appears after rain, a car wash or a jump start
  • Other network or low-voltage codes stored

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. TCM lost power or ground: blown fuse, corroded ground, loose connector 30%
  2. Water in the TCM connector or corroded pins 20%
  3. Low or unstable charging voltage from a failing alternator or battery 16%
  4. Damaged bus wiring between TCM and PCM 14%
  5. Failed TCM 12%
  6. PCM fault or software mismatch after a replacement module 8%

Diagnosis step by step

Diagnostic flow: P16981Read both modules2Check charging voltage3Inspect the TCM and its connector4Test power and ground at the TCM5Check the bus circuit6Replace and program only as a laststep

  1. Read both modules

    Try to communicate with the TCM directly using a scan tool that reaches transmission modules. If the TCM doesn't respond at all, focus on its power, ground and bus wiring; if it responds and has its own codes stored, diagnose those first.

    Tools: OBD-II scanner

  2. Check charging voltage

    Measure battery voltage with the engine running; it should sit roughly between 13.5 and 14.7 volts and stay steady with lights and blower on. Dips or spikes can knock the TCM offline, and a weak alternator is a known trigger for this code.

    Tools: Multimeter

  3. Inspect the TCM and its connector

    Locate the TCM for your model; on the Wrangler TJ it sits on the driver-side inner fender near the washer bottle, where water and dirt can reach the plug. Unplug it, look for green corrosion or moisture, clean the pins and check terminal fit.

    Tools: Screwdriver, Flashlight

  4. Test power and ground at the TCM

    With the key on, check battery and ignition feeds at the TCM connector and do a voltage-drop test on the ground circuits under load. A ground that shows more than a few tenths of a volt drop can let the module reset repeatedly.

    Tools: Multimeter

  5. Check the bus circuit

    With the key on, measure the bus voltage at the TCM connector and at the diagnostic connector; it should be present and similar at both ends. An open bus wire between the two modules is a wiring repair, not a module replacement.

    Tools: Multimeter

  6. Replace and program only as a last step

    If power, ground and bus all test good and the TCM still won't talk, the TCM is likely at fault. A replacement unit may need programming and a transmission quick learn so shifts are correct.

    Tools: OBD-II scanner

Where the parts are

Charging system and control modules – P16981234567
Charging system and control modules
  1. 1Battery
  2. 2Alternator
  3. 3Engine computer (ECM)
  4. 4CAN bus
  5. 5Transmission
  6. 6Wheel speed sensor
  7. 7High-voltage battery

Repair options & costs

RepairDIY?Estimated cost
Clean and reseal TCM connector, repair ground Yes $40–$180
Replace battery or alternator Yes $150–$600
Repair data bus or TCM wiring No $120–$400
Replace and program TCM No $350–$900

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Emissions / smog test impact

Will fail

P1698 turns on the check engine light, so the Jeep fails an OBD emissions test in states that test it until communication is restored, the code is cleared and the monitors have completed.

Frequently asked questions

Does P1698 mean my transmission is bad?

Not necessarily. The code only says the PCM stopped receiving messages from the TCM. Power, ground, connector and charging problems are more common than internal transmission damage.

Why is my Jeep stuck in second gear?

When the TCM loses communication or detects a problem, it defaults to a fixed gear to protect the transmission. The gear stays locked until the key is cycled or the fault is fixed.

Can a bad alternator really cause a transmission code?

Yes. The TCM is sensitive to voltage, and an alternator with a failing diode or regulator can make it reset or drop off the bus. Check charging voltage before replacing modules.

How is this different from U0101?

Both describe lost contact with the TCM. Newer vehicles on CAN networks report U0101, while older Chrysler-built Jeeps on the CCD or J1850 bus report P1698.

Sources