Engine wiring diagrams

Hi Danny,

Thanks for the prompt reply. I believe, a while ago, I came across the security system article that you sent me. I know I tried step 1 and 5 in the past without success. For step 5 (hard reset) I even left the battery disconnected (both positive and negative terminal) for many days but that did not fix the issue.
In your answer you said "after reading just scroll the page to find acura." I'm not sure if that means that I should only try the procedure in the "Acura and Honda security system reset information" paragraph or I should still try steps 2, 3, and 4. Kindly, clarify. By the way, regarding step 4 of the article (soft reboot of the immobilizer), do you know if it's fuse# 19 (under the dash) that I need to remove?
Another question that I have is, should pin 16 of the data link connector have 12 volts at all time (regardless of whether or not the immobilizer is activated)?
I will do the security system tests tomorrow and get back to you. Thank you again for your help.

Per Acura's service instructions, the procedure for testing 4-pin relays for the 2005 Acura TL is to connect power to pin 3 and ground to pin 4 and test for continuity. There should be continuity between pin 1 and 2 when power is supplied, and no continuity when no power is supplied.
I tested a lot of the 4-pin relays on the vehicle without any issue (as soon as power and ground are supplied to pins 3 and 4, I heard the relay click and was able to check for continuity between pin 1 and 2).
However, when I tried to test the Fuel Pump relay (which is also a 4-pin relay), as soon as power and ground were connected to pins 3 and 4, instead of hearing the relay click, I got a spark/arc and the alligator clip/wire almost melted from heat within one second. I tested about 6 different fuel pump relays that I got from the junkyard (All were Mitsuba relays, which were known to fail) and they all caused a spark instead of clicked. Is it possible that all the fuel pump relays I tested were defective (very unlikely or extremely bad luck) OR is the fuel pump relay supposed to be tested differently from all other 4-pin relays? And if so, please tell me how to test the fuel pump relay. Thank you.

Hi Sevag,

Thank you so much. I can't believe all fuel pump relays that I got were bad!
I have some follow up questions if you don't mind. First, will a bad fuel pump relay (main relay 2) trigger the immobilizer system (green key flashing)? Second, will a bad main relay 2 cause no communication with ECM/PCM when an OBD2 scanner is connected to the DLC? Third, is it safe to remove main relay 2 and insert a jumper wire in the fuse box socket where the relay goes? And if so, do I jump pin 1 and 2 or 3 and 4? Fourth, could you please upload the remainder of the diagrams (I attached a pic of where they end)? The diagrams I have are lower resolution quality than the ones you provided and they printed badly. Thank you in advance.

Hello,

I put a tested working main relay 2 (fuel pump relay) but that didn't solve the problem. I used a jumper wire between pin 1 and 2 and was able to hear the fuel pump activate, so there doesn't seem to be a problem with the fuel pump itself. I followed the article provided above by Danny to reset the anti-theft system, however that didn't work. I keep having the flashing key (anti-theft).
I tested the 5V reference at the MAP sensor connector and it did have 5v at the yellow/red wire and 0.02V at the green/white wire (ground). So, the ECU seem to provide the proper voltages to the MAP sensor.
With regards to the OBD2 connector, I did have power at pin 16, however there is nothing at pin 14 (I tried to test voltage between pin 6 and 14).
Any idea where to take it from here? Thanks

Hi KASEKENNY1,

I used a good scanner, when I connected it it powered up then, if I remember correctly, it came back with an error saying unable to communicate with ECM/PCM. At first, I thought maybe there was no power to pin 16. So, I tested pin 16 and found that it has constant voltage. Next, I thought maybe I have a bad ECM/PCM, that's why I did the 5v reference circuit test at the MAP sensor, to make sure the computer was working.
I tried to test voltage between pin 6 and 14 because I watched a YouTube video and wanted to test the CAN bus system. I didn't know there wasn't one. I'm glad you told me there is no wire at pin 6 because it didn't seem there was one and I thought for a minute that maybe my DLC was missing wires.
It's been a while since I did the tests, but I believe grounds on pin 4 and 5 were good. I will test again pins 4 and 5 at the DLC and will get back to you with my findings. Thanks

Hi Danny,

I didn't test the red/blue wire that you mentioned. What do I test for: voltage, continuity, or resistance? And what value(s) should I be looking for? Thanks

Hi KASEKENNY1,

I tested pins 4 and 5 before you replied, so I didn't use the method you mentioned. As far as testing pin 16, I used a metal bracket under the dash as my ground, and I measured 12 volts at pin 16. As far as testing pins 4 and 5, I connected a test light to the positive battery post and probed each of pins 4 and 5. The test light lit up, which means there is good ground at those pins. I will measure actual voltage at pins 4 and 5 and get back to you on the readings.
As I mentioned in a previously, I tested the 5v reference circuit at the MAP sensor, but based on the wiring diagram there seem to be 3 different 5v circuits (they may be internally connected) so I will have to test the other 2 circuits to see if they are alive. I learned that a bad sensor could cause the no communication error with the scanner. So, I will try to connect the scanner with as many sensors unplugged and see if that fixes the communication problem. But other than that, do you have any more suggestions? Thanks