02 Nissan Altima fuel injector N4 has short with ignition key on, injector leak
I am going to assume that you verified this by unplugging the injector and seeing constant power across the pins in that connector, and capmparing to the another good injector. if you have not done so. that is your first reading to take with a meter.
a breif description of how it typically works:
nomally, there is a single common for all the injectors. typically, it is a positive signal energised by the ecm/ecu either directly, or via relay. and usually fused. sometimes, on v8, and some v6's there are 2 commons. then, each injector is individually actuated through the ecu.
next test- if you find the common positive voltage, then the other wire should read nothing with the engine not runing. do an ohm check to ground. you will likely find that n4 only is reading continuity on the non-common wire. trace the harness to the main harness plug. it may be a disconnect in the engine bay, at the firewall, or a complete run to the ecm. unplug it. it may require wd-40 and some massaging fennesse. force is not the first answer to pulling it apart, and the clip may not release normally, reqiring a pick in there to unlatch it. if you still have continuity, then you have a short in the harness grounding between the 2 points. if you do not, then trace the wire from the connection point you disconnected, at least 5 inches away. you can do a pinout check, to find the correct wire. test all to verify you have the correct wire and then you will cut this wire, if you know you can reliably re-attach the wires together. before you do this, if it is not at the ecm test the corresponding pin at the other connection you unplugged from, to make sure you are not reading ground continuity (you may need to find the ground pin in that plug, as it may be the same plug that feeds the ecm ground.) then, unplug the ecm, and re-connect the disconnect, if applicable, and re-check continuity. now, you move to cutting the wire, if the ground is only present with the ecm connected. plug the injector back in and turn the key on. if you receive close to common voltage on the injector side of the cut wire and ground on the ecm side, then there is an internal short in the ecm/ecu. if the system uses a common ground, then all of this is inverted, with the positive battery/ign. as reference, not ground
Mar 10, 2012 |
Nissan Altima Cars & Trucks