The web site changed last week to a new format and the site host is having a huge problem with sending out automated e-mails letting you and me know when a reply is posted. What I've been doing is right-clicking then opening each new question I read in a new tab, then I leave those tabs open so I can refresh them later to see if a reply was posted. Unfortunately I have well over 100 tabs open and it has slowed my really old computer to a crawl. If it went any slower it would be going backward! It is common to take 5 - 10 minutes to switch to a new page.
Don't start a new question as that will just make it worse. I started getting a few automated e-mails this afternoon. I noticed both of yours came through. On the site they are listed as you replied last night, but I just got the message at 1:12 p.M. Today. Hopefully this will be fixed soon, then I may get flooded with hundreds of replies to answer. Sleep is over-rated anyhow.
As for your ASD relay, the 12 volts on terminal 30 is correct. That is the feed for the switched current to the injectors, coil pack, fuel pump, alternator field, and oxygen sensor heater. The 12 volts from the ignition switch to terminal 86 is also correct. That feeds the coil inside the relay. Terminal 87 does indeed need to be grounded but that is done by the Engine Computer. You can't measure that circuit for continuity. All you can do is watch its operation for that first one-second blip when you turn on the ignition switch. The easiest way to do that is to monitor the voltage we've been talking about from relay terminal 87 which goes to the injector, coil, etc. The second way is to feel if the relay clicks on, then clicks off one second later when a helper turns the ignition switch on. The third way, which is more time-consuming, is to place the probe of your test light on terminal 85 while the relay is installed, AND since you're testing for a ground, you have to move the test light's ground clip to the battery positive post. This way the test light will light up at the same time the relay is energized.
If any of those methods proves the relay is turning on for one second, that proves the circuitry is good and the computer has control of the relay. If the switched 12 volts shows up on 87 it should also be showing up at the coil and injectors. If it's at 87 but nowhere else, there has to be a break in that wire or a corroded splice.
Once you verify the 12 volts is showing up at the coil and injectors for one second, the next thing is it has to reappear during engine rotation, (cranking or running). If it does not, the computer isn't grounding the ASD relay terminal 85 because it doesn't know the engine is rotating. That is because a signal is missing from the cam or crank sensor or both. A scanner that displays live data will show both of them as "no" or "present" during cranking so you know which one to diagnose. If one signal is missing, suspect the sensor, its air gap, or a break in its signal wire. If both signals are missing, suspect a break in the 5, 8, or 10 volt wire that feeds both of them, a break in their common ground return wire, or the feed wire is shorted to ground by a pinched wire or shorted sensor. That feed voltage should be present all the time the ignition switch is on. If you don't find it at either sensor, unplug them and measure on the plugs after turning the ignition switch off and back on. If the wire or either sensor grounded out that feed line, the computer shuts that power supply down to protect it. Once the short is removed, you have to cycle the ignition switch off and back on to reset it. Missing the supply voltage to the sensors is not very common so we'll address that later if it becomes necessary.
Just for information purposes, you need 12 volts from the ignition switch to relay terminal 86 AND the ground on 85 to energize the coil inside the ASD relay. That is a double safety circuit and is extremely reliable and effective. In a crash that ruptures a fuel line, the engine can't run without fuel pressure so it stalls. That means no pulses from those two sensors so the computer turns the ASD relay off. That removes the 12 volts going to the fuel pump, or, on some models it also turns off a separate fuel pump relay along with the ASD relay. Either way the pump stops dumping raw fuel onto the ground where it would be a fire hazard. That wire between the computer and terminal 85 is only a few inches long but if it somehow got pinched or someone tried to modify it, the relay would still get turned off by turning off the ignition switch.
Unfortunately there is no easy way to know if the pulses are being received by the computer except with a scanner.
If you do find steady voltage at the coil and injectors during cranking, that indicates you have a less-common problem with one of the three individual circuits, the ignition coil, injector circuit, or the fuel pump. Of the three a dead fuel pump is the most likely suspect. You won't hear it hum for that one second after turning on the ignition switch. The coil pack would be next. You would have no spark but you would have good fuel pressure and you'd smell the raw fuel. If all the injectors were dead, suspect a break in the common wire feeding them from the ASD relay. Failure of one driver circuit in the computer is rare, and a total failure of all four, six, eight, or ten is unheard of. More commonly that would be caused by a blown fuse feeding the computer.
Monday, October 29th, 2012 AT 9:49 PM