OBD reader does not power up

ERNIE5599

MEMBER
1995 MAZDA PROTEGE
1.5L
4 CYL
2WD
AUTOMATIC
266,970 MILES

My obd reader not working. Checked all fuses they are all good and replaced main fuse under hood and nothing. Oh and the horn isn't working but it does when alarm goes off.

1 Reply

JACOBANDNICKOLAS

EXPERT

Hi,

I attached two pics related to power supply. Check the fuses I circled. Also, note in picture 2 that power goes to the horn relay via the DLC under hood.

Pics 3 and 4 are the entire data link connector schematic. I had to cut the schematic in two so it was readable for you. I did overlap the two to make it easy to follow. In pic 4, I circled two grounds. If you find the fuses are good and power is being distributed, confirm the ground is good.

________________________

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If you want to check the horn relay, here is a link that explains how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find.

Take care,
Joe

Images (Click to enlarge)