How does one Troubleshoot the Heater Grid circuit ??

 

The Haynes manual has an excellent section on testing the entire system. It steps you through each component. You'll need a digital multi-meter.

 

Not a complicated system. The temp has to be low enough to turn them on to T/S much. There are ways around that though. What is the issue your having?

Basically, if the air temp sensor says it is below a given temp (and speed) the computer with send a small current to one of the two relays on the fender. You can check for that Voltage between the two little wires. If you have V you should hear/feel (if your hearing is lacking) the relay click. If you look at the top of the relay you'll see the wires that go directly to the battery. As long as there is not something (corrosion/damage{which would likly make spark}) you should have power to the relay. You can check V on both sides of the large connectors (top) of the relay.

Remember they cycle on and off so it won't be a constant V.

Randy

 

Check the small blue wires that plug in on top of relay first. You may just need to squeeze the connector with pliers to fix the problem, they work loose.

 

I'll give you a general way , do have info at hand for specific yr-mld , use a test lite to see if theres power at the connections of heater when the outside air is low enough to turn on , if there is power then disconect the wires and check the resistance [ not sure what it should be ] at least not open .
If no power then you've got 2 places to go the sensor , to send signal to opperate , and then the relays that turn it on direcally [ maybe the most comin failure ].
Try to get ahold of a wiring diagram , big help in following the path of opperation , with a little cominsence you can use it to diagnose .