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Discussion Starter · #1 ·
I have a 2002 EX; that will start and run perfectly if I have the OBD2 reader plugged in. It will also run perfectly if I jump pins 4 and 5 on the port.

Other ways it will not start at all, the ignition key light, the check engine light, and the battery light won't come on ether.

So it seems its a problem on the terminals of ether one of this pins, but I am having problems finding where in the car do they ground, Am i approaching this correctly? and if so where do they ground?, I believe one goes to the chassis somewhere and the other near the ECU ?
 

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17 CRV EXL AWD, 14 CRV EXL AWD
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Yes, you are approaching this problem correctly. On the OBD2 connector, pin 4 is chassis ground and pin 5 is signal ground. Pin 4 runs straight to chassis ground and is only used by a scanner plugged into the port...It is not needed to operate the vehicle. However pin 5, signal ground, is used by a ton of devices. Pin 5 does eventually get tied to chassis ground, but not until it passes thru some junction points where other devices tap off of this line and then gets tied to chassis ground. You can check this by connecting a dvm and read continuity between chassis and pin 4 and pin 5. I will bet pin 4 reads to chassis but pin 5 doesn't and it should. By jumping pins 4 and 5 you are bypassing around the broken chassis connection on the signal ground line.
Now for the bad news, I don't have a service manual for your gen CRV so I can't tell you where the signal ground is physically tied to the chassis and the junction points it passes thru.
I've attached two diagrams which show the OBD2 port (Honda DLC port) and the signal ground distribution that pin 5 is tied to. But this is for a 2008 CRV
 

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Discussion Starter · #3 ·
Yes, you are approaching this problem correctly. On the OBD2 connector, pin 4 is chassis ground and pin 5 is signal ground. Pin 4 runs straight to chassis ground and is onled by a scanner plugged into the port...It is not needed to operate the vehicle. However pin 5, signal ground, is used by a ton of devices. Pin 5 does eventually get tied to chassis ground, but not until it passes thru some junction points where other devices tap off of this line and then gets tied to chassis ground. You can check this by connecting a dvm and read continuity between chassis and pin 4 and pin 5. I will bet pin 4 reads to chassis but pin 5 doesn't and it should. By jumping pins 4 and 5 you are bypassing around the broken chassis connection on the signal ground line.
Now for the bad news, I don't have a service manual for your gen CRV so I can't tell you where the signal ground is physically tied to the chassis and the junction points it passes thru.
I've attached two diagrams which show the OBD2 port (Honda DLC port) and the signal ground distribution that pin 5 is tied to. But this is for a 2008 CRV
Thank you very much! You provided tons of help, and quite a bit of relief, I just had the AC repaired and they cleaned the evaporator core, i believe the ECU, is right by it and I believe that is when this problem started, anyways, appreciate your help alot!
 

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