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GTECH Calibration
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P1498

High speed Rad Fan Ground CTRL Rly Circuit.

  • Pontiac
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
98
FaultThe specific fault in that area

What it means

On a Pontiac, P1498 points to a fault in the high speed radiator fan ground control relay circuit. The engine control module commands this relay to switch the ground for the high speed cooling fan, and it has seen a voltage or state on the circuit that does not match what it commanded. The exact relay layout and fan configuration depend on the model and engine.

Symptoms

  • Engine temperature rising in traffic or at idle
  • Cooling fan not running at high speed
  • Cooling fan running constantly or at high speed when the engine is cold
  • Air conditioning performing poorly when stationary
  • Engine warning light on
  • Temperature gauge reading higher than normal

Possible causes

  • Faulty high speed fan ground control relaylikely
  • Damaged, chafed or corroded wiring in the relay control or fan ground circuitlikely
  • Poor connection or corroded terminals at the relay, fuse box or fan connectorlikely
  • Blown fuse or fusible link supplying the relay or fan circuitpossible
  • Faulty cooling fan motor drawing excess current or shortingpossible
  • Fault within the engine control module driver for the relayrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting engine temperature and whether the air conditioning was on when the code set
  2. Check the relevant fuses and fusible links in the fan circuit against the wiring diagram for the specific model and engine
  3. Visually inspect the relay, its socket, the fan connector and the wiring for heat damage, chafing, water ingress and corrosion
  4. Command the high speed fan on with a scan tool or by the manufacturer's test procedure and note whether the relay clicks and the fan responds
  5. Swap the relay with a known good one of the same type, if the layout allows, and retest
  6. Check power, ground and control signal at the relay socket with a multimeter, following the wiring diagram
  7. Test the fan motor current draw and ground path, and check for voltage drop on the ground side
  8. Check the control module output and wiring continuity only after the relay, wiring and fan have been proven good

How to fix

  • Replace the faulty fan ground control relay
  • Repair or replace damaged wiring, and clean or renew corroded terminals and connectors
  • Replace blown fuses or fusible links only after finding and correcting the cause of the overload
  • Replace the cooling fan motor or assembly if it is shorted or drawing excess current
  • Repair or replace the engine control module only once all other causes have been ruled out and the fault is confirmed

Can I keep driving?

Medium severity

Short, gentle journeys are possible if the temperature stays normal, but without a working high speed fan the engine may overheat in traffic. Get it fixed soon, and stop if the temperature gauge climbs.

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

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