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P1287

Fuel Injection Pump Controller Supply Voltage Low.

  • Jeep
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
87
FaultThe specific fault in that area

What it means

On a Jeep, P1287 means the fuel injection pump controller (the driver module that operates the injection pump on diesel engines) has seen its supply voltage fall below the expected level. The engine control unit sets the code when the voltage feeding that controller is too low for it to work reliably. The cause is usually a power, earth or connection problem rather than the pump itself, though the exact layout depends on the model and engine.

Symptoms

  • Malfunction indicator lamp on
  • Hard starting or long cranking
  • Engine stalling or cutting out
  • Loss of power or limp-home mode
  • Rough running or hesitation
  • Intermittent fault that comes and goes with electrical load

Possible causes

  • Weak or poorly charged battery, or corroded or loose battery terminalslikely
  • Poor connection or high resistance in the supply or earth wiring to the pump controllerlikely
  • Corroded, loose or damaged connector at the pump controller or its fuse and relay circuitlikely
  • Charging system fault such as a weak alternator giving low system voltagepossible
  • Faulty fuse, relay or power feed supplying the pump controllerpossible
  • Internal fault in the injection pump controllerrare
  • Wiring harness damage from chafing or water ingressrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, including battery or system voltage when the fault set
  2. Check for other charging, battery or communication codes that point to a wider power supply issue
  3. Inspect battery terminals, main earth straps and the engine earth for corrosion, looseness or damage
  4. Test battery condition and measure voltage at rest, while cranking and with the engine running to confirm the charging system is working
  5. Check the fuses and relays for the pump controller circuit and inspect them for heat damage or poor contact
  6. Inspect the pump controller connector and harness for corrosion, bent pins, water and chafing
  7. With the engine running and a load applied, measure voltage and voltage drop on the supply and earth at the controller, using the wiring diagram for that model and engine
  8. If supply and earth are good, follow the manufacturer's procedure to test the controller before replacing it

How to fix

  • Clean and tighten the battery terminals and earth connections, or replace damaged cables
  • Replace the battery if it fails a load test
  • Repair or replace the alternator if the charging voltage is low or unstable
  • Repair damaged wiring or connector pins and replace faulty fuses or relays
  • Replace the injection pump controller only after confirming a good supply and earth, then carry out any programming it requires

Can I keep driving?

Medium severity

The car may run normally for a while, but it can stall or lose power without warning if the voltage problem gets worse. Get it checked soon and avoid long journeys until the supply fault is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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