I've had my 89 350 SRW parked for about two months and I'm just started driving it on a more regular basis and I noticed that my grid heater isn't working. The light on the dash doesn't come on but the buzzer does sound but I don't hear the normal clicking. Is my best bet buying a new grid heater or is it more likely that something else is causing it. The truck has 164k and eveything else is functional. Thanks in advance.

Where the best place to purchase items like this? I also need parking brake cables for the truck.

 

The first trucks didn't kick on the grid heater until 15 degrees. To check that the system works, unplug the air temp sensor and turn on the key. You should hear the relays click and the WTS light should flash.

 

Wanna, which sensor/connector is that?

 

Dave, your system works different. I don't know that unplugging the sensor is a valid test for the PCM systems, this test is for the old brain boxes on the firewall.

On an intercooled truck, the air temp sensor is one of two on the manifold behind the intake elbow. One is the KSB switch, the other is the IAT sensor for the PCM. I'm posting from my Dad's place out in IL so I don't have the FSM to look and see which is which.

On non-intercooled trucks there's just one sensor back there, the brain box uses that input to run the grids and the KSB. Unplugging the sensor puts it in self test mode.