Jeep PWM Fan Relay Test Troubleshooting An Overheating Condition

This tutorial leave help you to diagnose the Pulse Width Softened (PWM) sports fan relay on the 1999-2003 Jeep 4.0L Grand Cherokee SUVs and/operating room the codes P1491 (Radiator Fan Command Relay Circuit).

The bargainer, at the time of this writing, will institutionalise you $95 (US) to name it. Only if you have more prison term than money, you rump easily diagnose it yourself, and I'll show you how.

Testing the fan relay is easy, the hardest set out is getting to it, since Jeep in all its wisdom, set the fan relay in arrears the right broadside (passenger incline) of the front bumper and you'll probably have to remove it to access it.

You butt pay Jeep an arm and a leg to set information technology, or you can, with my assistanc, diagnose and repair the issue yourself, hold open that money and spend it on something like tools.

En Español You fanny find this teacher in Spanish present: Cómo Probar El Relé PWM del Ventilador (4.0L Landrover) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the followers vehicles:

  1. 1999, 2000, 2001, 2002, 2003 4.0L Jeep Extraordinary Cherokee.

RELATED WIRING DIAGRAM:

  1. Radiator Sports fan Motor Circuit Wiring Diagram (1999-2003 4.0L Jeep Grand Cherokee).

Important Tips

TIP 1: The mode I've fashioned the Landrover PWM fan electrical relay test, you'll indigence a scan tool that give the sack read live data (not a code lecturer), since you'll need to keep an eye along the engine's coolant temperature with it.

You DO non need the Jeep factory scan tool, just a generic skim tool that you can buy out at your local auto parts store or online and a multimeter. Forthwith depending on your level of 'wrenching feel for', you can modify this test soh that you can behave it without a generic CAT scan puppet (and I leave this finished to you).

TIP 2: Information technology's very important that you first out with a unloving engine. If you have a skim tool, verify that the locomotive engine coolant temperature (ECT) value is low 190° F. If the engine has been running for an protracted period of time, let IT cool down for about 1 hour operating room more.

TIP 3: Before you jump into the tests, take a look at and interpret the entire clause so that you'll know what the psychometric test is all about and what you'll pauperization to do.

TIP 4: The very first thing that you need to test/verify, is the sports fan. You need to physically see it derive on by directly applying 12 Volts to it and if the fan drive does near, calculating its amperage draw (and I'll show you how).

TIP 5: Also, you're not gonna' see whatever 'absent and replace' type instructions since the clause is all about the diagnosing the relay, non how to transfer and replace information technology. And so you may give birth to buy a repair manual or do promote research online.

Symptoms Of A Bad PWM Fan Relay

The most obvious symptom of a badly PWM fan electrical relay is that your Jeep is gonna' overheat.

You'll also see one or all of the pursuing symptoms as the engine overheats:

  1. The electric radiator fan motor does not amount along.
  2. Coolant bubbling out of the coolant artificial lake.
  3. Temperature gauge on the instrument cluster is maxing out.
  4. Chequer engine light (CEL) is on and:
    1. DTC P1491 stored in the computer's memory

If your Landrover overheats beyond a certain point, you risk blowing the head gasket and/or cracking the cylinder top dog.

Thankfully, testing the PWM fan relay fire be easily through right at home, without the need of taking it to the Jeep house.