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DTC codes / Jaguar codes / P1637

P1637 · JaguarCAN Link ECM ABS Control Module Circuit Network

P1637 on a Jaguar indicates that the engine control module (ECM) cannot communicate with the anti-lock braking system (ABS) control module over the controller area network (CAN) bus. The ECM sets this code when it detects a loss of the CAN link or an invalid message from the ABS module, often due to a wiring fault, module failure, or power/ground issue.

SystemPowertrain
Code typeJaguar specific
SeverityMedium
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • Anti-lock brake system (ABS) warning light illuminated on the dashboard
  • Traction control warning light may also be on, as it often shares the ABS module
  • Speedometer may stop working or behave erratically if the ABS module provides the vehicle speed signal
  • Transmission may shift harshly or enter limp mode due to missing wheel speed data
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Electronic stability control (ESC) or dynamic stability control (DSC) warning light may illuminate

Common causes, most likely first

  1. Damaged or corroded wiring in the CAN bus circuit between the ECM and ABS module
  2. Faulty ABS control module (internal CAN transceiver failure or power/ground issue)
  3. Blown fuse or poor ground connection for the ABS module
  4. Water intrusion or corrosion at the ABS module connector
  5. Failed ECM (less common, but possible if CAN output is faulty)
  6. Aftermarket accessories or poor previous repairs interfering with CAN wiring

How to diagnose and fix it

  1. Perform a visual inspection of the ABS module connector and CAN wiring for corrosion, damage, or loose pins
  2. Check all fuses and relays related to the ABS module and ensure they are seated properly
  3. Measure battery voltage and ground integrity at the ABS module connector
  4. Use a scan tool to check for communication with the ABS module; if no communication, proceed to circuit testing
  5. Test CAN bus resistance (should be approximately 60 ohms) and check for shorts to ground or power
  6. Perform a wiggle test on the wiring harness while monitoring live data for the ABS module communication
  7. If wiring and power/ground are good, substitute a known-good ABS module or ECM to isolate the faulty unit

Before you replace the ABS module

  • A common cause of P1637 is a corroded connector at the ABS module, often due to water ingress from a clogged sunroof drain or faulty windshield seal, which is frequently overlooked.
  • The code can be set by a weak battery or charging system issue that causes momentary voltage drops, disrupting CAN communication without any permanent wiring fault.
  • On some Jaguar models, the ABS module shares the CAN bus with other modules, so a fault in another module can sometimes mimic a direct ABS module failure.
  • After replacing the ABS module, programming or coding may be required for it to communicate properly with the ECM, and a used module may not work without dealer-level software.
  • P1637 can be an intermittent code that only appears under certain conditions, such as during cold starts or when the vehicle is driven over rough roads, making it important to check for loose connections.

Can I keep driving with P1637?

If the brake pedal feels normal and the ABS warning light is the only symptom, you can drive cautiously to a repair shop, but avoid heavy braking or slippery conditions because the anti-lock braking system may be disabled. If the brake pedal is spongy or the vehicle exhibits other braking issues, stop driving and have it towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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