2006 Toyota Sienna
I recently repaired and recharged the a/c on this van. A week later the a/c has quit. The system is still fully charged but a/c wont turn on. I discovered that signal from the ecm would not trigger the relay. I checked the resistance and got 33k ohms , I disconnected the wire from the ecm and had zero ohms from ecm to the relay. If I ground the wire at the ecm the a/c works fine. Is the ecm the problem, can I program a used ecm for this van
Is there a pressure switch pid? Have you confirmed with scan data that the ac is being requested on?
You need scan tool to see the ECM is getting all the correct inputs before you condemn the output.
There is a difference between a request from the panel control than an actual execution of that request. As the other techs mentioned. Check your sensors voltage reference. PS: if you back probe wires and ground the circuit you may actually damage the Ecm. And you might end up with 2 issues. hope you solve it🥋
Can you active test the compressor with a scan tool? A lot of times the active test bypasses any inputs. it’ll show you if the ecm has the ability to turn on the compressor, and let you know if it’s an input issue.
I've ran into an issue where the control module wasn't seeing compressor rpm from the hall effect in the compressor.
If A/C request is being sent by HVAC control to ECM then more than likely the ECM does not like what it sees and preventing relay activation. Be sure to test all A/C inputs to ECM before condemning .
a B1422 code may have been stored. you connect between pins 1 and 2 of the 3 pin connector the resistance must be between 65 and 125 ohm also check the waveform scale 500 millivolts and 20 ms div you must have a signal
Hello Sid, These have a self-check mode by pressing the button combination on the AC control head that is listed in the service information. It is likely the system is seeing a signal that is not good, so the AC is disabled until the problem is corrected.
Ok this may sound stupid, but the ecm is supposed to send a ground signal to the relay. I have no codes on any module in the van. So with the van running and everything plugged back in the a/c still would not work. So I put a ground jumper to b2 pin of the ecm which feeds the relay , since I did the jumper only for a few seconds as a test the a/c has worked fine without the jumper. i can cycle…
Quite possibly a sticking relay, which is not uncommon on these, either when commanded on, or off, they can fail either way, intermittently. Resistance testing tells you not a lot about whether the PCM can actually do the job. But, you've temporarily ‘repaired’ it. Would've been nice to see what the voltage was at the PCM, and whether it actually attempted to ground the coil side…that said, a…
Hello Sid, I'm with Timothy M. on this one. At the very least it might be wise to replace the relay and perform multiple run cycles before releasing this back to the customer. I have also seen control buttons that were “muddy” from people who like to use too much hand lotion and it would make the button sticky and not function properly. Simply cleaning the control head may also help.
Thanks for all the suggestions, this van owned by a gentleman, so I think hand lotion wont be the case lol. I am kind of stuck in limbo on this one as I probably wont see the van again unless it malfunctions again. i had already replaced and even load tested the relay
Hi Sid, Funny has it may sound, I used Vaseline Intensive care hand lotion each time I wash my hands, especially in the Winter. Personally, I cannot stand to work with dirty hands. It really makes me cringe when I see other techs in this trade who will eat their food with grease-stained hands. I am not “Mr. Clean” but I try to take care of myself. I've seen too many techs over the years have to…
Hi Sid, In that event, go ahead and close this as resolved.
I am trying to figure out how to mark this as solved any guideance would help
Sid I think to close/resolve this, you go to your post 2 days ago where you state: Well, the van has never returned so I guess it is solved. In the post you (and only you or the admin) have the capability of clicking on that post as “RESOLVED”. I think it then turns it a light shade of green.
Hi Sid, replying to your original question will provide you with the opportunity to mark the message accordingly.