I replaced the switch and the bulbs but can not get the high beams to come on. For what and where do I need to look. Help!
Thank you!
Which relay though? I can't find a relay with a name that would indicate it's for the high beams or DRL.
Page 408 of the owner's manual shows 3 fuse box locations for the 2012 Accord Coupe.
The interior driver's side fuse box has the fuse for the DRLs. The interior passenger's side fuse box has the fuse for high beams. (relays are typically located in fuse boxes): http://techinfo.honda.com/rjanisis/pubs/OM/E01212/E01212OM.PDF
Correction*
Left Headlight high beam fuse is in the interior driver's side fuse box.
Right Headlight high beam fuse in in the interior passenger's side fuse box.
Thank you!
The high beam circuit doesn't use mechanical relays. It uses IPDs (Intelligent Power Devices) soldered onto the circuit boards of the driver's side MICU ((inside the driver side underdash fuse box)) (((for the driver's side high beam headlight))) and the passenger side MICU ((inside the passenger side underdash fuse box)) (((for the passenger side high beam headlight))).
System Description:
The Driver's Side looks like this. I highlighted Power in Red and Ground in Green. The Driver's side MICU communicates with the Passenger side MICU over the B-CAN (communication) bus (( I didn't highlight it but it's those dotted lines on the diagram)) . Headlight switch ON, Ground is provided to terminal 8 of the Driver Side MICU.
High Beams are selected and Ground is provided to terminal 22 of the Driver Side MICU. Then, like the description says, both MICUs energize the individual High Beam circuits through their individual High Beam IPDs.
So getting back to that first image I posted comparing Mechanical Relays to IPDs. The last line of text is important. "....but protection as well by detecting overcurrent"
It detects overcurrent really well. And when it does the MICU de-energizes the circuit to protect it AND sets a code. The code will have a "B" prefix (Body code).
And with these lighting circuits, even after you fix the problem, as long as the code(s) remain, the MICU won't energize the circuit until the code is erased.
Maybe before you break out the test light and start checking the Power on the fuse tabs, MICU terminals, and high beam headlights and the Grounds on the Combination switch, MICU terminals, and high beam headlights, grab a scanner that can read and erase body codes on your Accord and see if there's any set.
Thank you for the help. Much appreciated ! Off to the dealership then....
Interesting read @jack62 . Shocked at the complexity of headlight circuits. I have a question.. Are the fuses on these circuits designed to protect the MICU?
Yes. As well as the rest of the circuit. When you look at the 2nd part of his wiring diagram it shows that Fuse 28 (10 amp) protects the load side of the left side high beam circuit which includes that IPD in the MICU
.
I believe I understand. The fuse rest in relay/boxes but still protects the entire circuit, including the IPDs, MICUs, HL switch and lamps. Errors/faults are recorded by ECM, and if too much amperage, blows fuse?
check the fuses + relays
Thank you!
Which relay though? I can't find a relay with a name that would indicate it's for the high beams or DRL.
