Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Greetings all. I'm working on a 2003 Highlanders O2 sensor heater circuit. Looking at the wiring diagram I am trying to figure out which control just the heater circuit and which ones are for the sensor signal. Here is what the connector diagram shows. #1 is Blk which comes from the ECM as HAFL, of which I assume is Heater Air Fuel Left for the B2S1 heater control?... # 2 wire is Red/Wht which comes from the relay for 12 V power, #3 is green from the ECM which is positive, and #4 is Red coming from/or to the ECM as negative. Can somebody explain this a little better for me? I really would appreciate it. Thanks, Doug
Hello again, nevermind on the descriptions of the circuit. I just watched Pauls video on the Lexus part 2, wideband sensors testing in the wiring diagram that he used to live there showed better detail of the system. Identifix wasn't that self-explanatory to me but now it makes more sense where connections 3 and 4 are for the positive and negative sensor signal connections. And connections one and two are for the 12 volt power for the heater and the pull-down design computer control which is the HAFL connection. ONE QUESTION IS THOUGH WHAT DOES THE L STAND FOR? Sorry about that was still on all caps. Thanks again, Doug
Looking at the diagram, I'm guessing that the 'L' in HAFL designates Left, as in the left bank of the engine. The other upstream heater control is HAFR. Toyota has always been kinda goofy about their circuit designations. :silly:
Yeah that's what I was thinking... Some manufacturer's do a good job with labelling well and other's sure don't! I had a fairly good list of abbreviations and their meanings of these for my Toyota once, I think it was from snap-on, but it went the way of my lost phone. Does anyone know of any good information on the net that someone has compiled for various makes and their somewhat obscure abbreviations?
Topic Author
