Where to connect AFR sensor?
OK here is the deal. There is only ONE switched 12V "ignition run" and that comes from the ignition switch. But that line is already over-taxed and is the reason many of these girls overcharge the battery--because voltage drop in that circuit under-feeds the VR and the VR ramps up the charging voltage "because it thinks" the voltage is low
So do yourself a favor and add a relay for the under-hood ignition loads. Find the "ignition run" line coming out of the bulkhead connector. This is dark blue most years but not always. This feeds the ballast resistor, the VR IGN line, the alternator field, and smog devices some years.
Break this wire, now you have the "bulkhead" / firewall end and the engine bay harness end. Feed the bulkhead end (from the key) to the coil of a Bosch relay. Feed the relay contacts with a big fuse or breaker, say 20A from the "big stud" on the starter relay. Ground the remaining coil terminal, and connect the load terminal (NO) to the other end (engine bay harness end) of the "igntion run" wire. That point is also where you want to feed to your sensor.
Also pay attention to grounding instructions on that device. It can pick up electrical noise if not. I believe you want it grounded to engine block, "same as battery"
Bosch relay terminals:
85---coil ground
86---to switched 12V IE the cut end of the "run" wire coming out of the bulkhead/ firewall
30---to fuse and to starter relay "big stud" IE 12v constant power
87---to engine bay cut "run" wire harness side, and to your o2 equipment
74 Bulkhead connector
Terminal "N" no. 16 Dark BLue is what you want---what they call the "J2" circuit
OK here is the deal. There is only ONE switched 12V "ignition run" and that comes from the ignition switch. But that line is already over-taxed and is the reason many of these girls overcharge the battery--because voltage drop in that circuit under-feeds the VR and the VR ramps up the charging voltage "because it thinks" the voltage is low
So do yourself a favor and add a relay for the under-hood ignition loads. Find the "ignition run" line coming out of the bulkhead connector. This is dark blue most years but not always. This feeds the ballast resistor, the VR IGN line, the alternator field, and smog devices some years.
Break this wire, now you have the "bulkhead" / firewall end and the engine bay harness end. Feed the bulkhead end (from the key) to the coil of a Bosch relay. Feed the relay contacts with a big fuse or breaker, say 20A from the "big stud" on the starter relay. Ground the remaining coil terminal, and connect the load terminal (NO) to the other end (engine bay harness end) of the "igntion run" wire. That point is also where you want to feed to your sensor.
Also pay attention to grounding instructions on that device. It can pick up electrical noise if not. I believe you want it grounded to engine block, "same as battery"
Bosch relay terminals:
85---coil ground
86---to switched 12V IE the cut end of the "run" wire coming out of the bulkhead/ firewall
30---to fuse and to starter relay "big stud" IE 12v constant power
87---to engine bay cut "run" wire harness side, and to your o2 equipment
74 Bulkhead connector
Terminal "N" no. 16 Dark BLue is what you want---what they call the "J2" circuit
