Won't Start - checked these things - ECM suspected?

Sharon. not only have I told you but others as well. The tan wire is the ground. The red is the "hot side". Look at your schematic. Follow the red wire. Notice that it goes to a dot ( that is a junction ) with other wires merging into it? keep following. It goes to the EEC relay. As I told you the EEC relay powers the fuel pump relay. If you keep following the red wire it also powers the injectors the thermactor solenoid the canister purge solenoid just to name a few items. If you take the time to look say at an injector harness you will notice it has one red wire. That is the same circuit as the red wire on the fuel pump relay and EEC power relay. It will show 12 volts when the key is in the run position, try it. So I'll say it again. Put the key in run and test the red wire. Do you have

12 volts? I'll assume yes. Put the test lead on the tan wire with the key in run, do you have 12 volts, I'll assume yes, and that is what you should see. Keep the test lead where it is at and turn the key to crank ( crank meaning you are starting the engine ) the voltage should drop to 0. I'll assume that is what is happening by your past posts and that is what you want to see. You do not have a fuel pump gauge? You need one. You will not know for sure if the pump is doing what it is supposed to do with out it. So if you put the meter on the tan wire and got 0 volts

read on..........posted 11/12/03 @ 7:22pm

"As mentioned before, the tan wire is the relay primary ground. With the relay in its socket, put a test lead in the tan wire and put the other test lead to a ground, turn the key to RUN do NOT turn the key to crank!, do you have 12 volts? Yes or no? If yes THEN turn the key to crank. Do you now have less than 12 volts, if yes what is it? If it is below 12 volts like say 1 or less, that is normal and the circuit is working correctly. If it stays 12 volts get back to me."

If you do not understand, please say so. If you do not understand please let me know what you do not understand.

Reply to
Thomas Moats
Loading thread data ...

Reply to
Thomas Moats

Reply to
el lobo

Reply to
Thomas Moats

and crank engine. Does the 12v light come on?

Reply to
Scott

For the test method you are using the engine must be running.

Bill

Reply to
berkshire bill

1) I get a little confused because of all of the acronyms and names used for the same part. By the ignition module, do you mean the ignition module/control unit that sits on the side of the distributor, needs a special tool to dismount, and special goop to remount? 2) I retold you something yesterday that I had already told you and I wanted to know the implications of this. When I was checking through the wiring, as was suggested, I found absolutely no voltage, at any time, coming out of the tan wire on the outgoing side of the fuel pump relay
formatting link
(The incoming red wireshowed me a full 12 volts.) You, or someone else had mentioned, that I wouldget a little hit on the meter when I first tried to start the engine (turnthe key all the way). I did not get this blip. I tried several times andhooked the meter up through a jumper clip jammed into the housing for thatwire. I even removed the insulation from that wire and tested it that way.Nothing registered, no blip. Could you tell me what that would imply toyou? Thanks and take care, Sharon
Reply to
Sharon

I do not have a test light, but I do have a multimeter. I was able to disconnect one (broke one side of the hold down because the plastic is very brittle). I put a jumper wire across the two terminals, put an alligator clip lead from there to the positive side of my multimeter, then grounded the other side to good ground. Cranked the engine. The meter went to 12 volts. Meaning, I am getting electric flow to the injectors.

I have no fuel gauge and can't find the connector on the fuel rail anyway. Thanks Neil.

Take Care, Sharon

Reply to
Sharon

I couldn't agree more. I have been saying that for a while. I think the connector is bad and may have been bad. Could have gotten blown when something shorted. God knows.

Yes, and got replacement relays 3 times already.

Stan, could you tell me how?

Yes, starts like a charm.

Thanks, Sharon

Reply to
Sharon

Got the click and the other two terminals read 1 ohm when set on the RX1K setting. Relay is good. Now I have to check out the socket that holds them (again). Take Care, Sharon

Reply to
Sharon

That tells you that either the red or the tan/lt grn wire is not conected to the coil in the relay. Could it be that when you put nails is the conector you spread the contacts open and now they are loose fit on the relay? Did you try putting the original fuel pump relay back in? I would test the new and old relays with your meter and the battery to see if they are the same and if they work. Will the car still start with starter fluid? Stan

Reply to
Stan J.

cranking). That wire is what the ECM grounds to turn on the pump. I think your next step is to connect your test light to the orange wire, ground the tan wire and crank the engine and see if you get a light. If you do the ECM (computer) is not telling the pump to come on. If you dont get a light, with the tan grounded and you do have power to the red wire and yellow wire with the engine cranking that means the relay is bad. Sooo If you do get that light then you have a bad connection from the ECM to the tan on the relay, or a bad ECM, or a bad connection from the ignition module to the ECM, or a bad ignition module, or .....So does it light up?

Reply to
Scott

I put my multimeter on it and hooked it up the way you told me to hook up the light. I got a reading on the multimeter, but it was very weak. Could be the difficulty I had getting a good connection through the back of the wires, or could be the socket (which has been my guess all along the last couple of days). I think I am going to go buy a new connector and try that, just to satisfy my own instincts.

Thanks and take care, Sharon

Reply to
Sharon

The terminal that goes to the red wire hook to positive 12 volts.

The terminal thet goes to the tan/lt green wire hook to negitive 12 volts.

It should make a click when you do this.

The other two terminals should now read near 0 ohm's from one terminal to the other on your ohm's meter if the relay is good.

Stan

Reply to
Stan J.

In article , "Sharon" wrote:

What you did was to short the injector circuit, not a very good thing to do (may have smoked the injector drivers). Even installed the way I described, a mechanical volt meter would probably not be able to respond to the injector signal fast enough. I had no doubt that you had voltage supplying the injectors, you proved that when you checked voltage to the red wire going to the fuel pump relay since that is the exact same circuit that the EEC relay switches on to power up all the various driven devices in the system. What needed varification was whether the injectors were being signaled -by- the engine computer, the easiest down and dirty way to do that is to substitute a light bulb in place of the injector. If you'd have mentioned that you didn't have a test light, you could have been directed to scrounging one of the vehicles side marker lights to use as a substitute. Since I know for a fact that a side marker bulb only draws 1/4 amp, this would have facilitated a safe test method and it would have only been at the expense of an (temporarily)inoperative side marker. If you don't have a tool to do a test with or are unclear on how we're describing to hook it up, please, please, please, stop, post back for clarification or for a way to fabricate or substitute. You can't begin to imagine how easily the integrated circuits can be fried inside the engine computer by performing a test wrong or by substituting a different piece of test equipment.

Can you borrow one from the AutoZone store?

Reply to
Neil Nelson

Reply to
Thomas Moats

That is normal, when the voltage goes through it's load, i.e., the coil of the relay and the circuit is grounded, you get 0 volts. If the ground circuit was open, you would see 12 volts, because it is not a complete circuit. When you see that the circuit is ok.

By making a ground, you are completing the circuit, energizing the relay, you will see 0 volts.

Then the relay is bad or wrong. Or the ECM is making ground all the time. Release the tab that holds the tan wire in the relay socket to make sure the wire is not broken at the terminal if that is ok put it back in the socket and one more test. With the relay in it's socket, cut the tan wire in a place you can splice it back together. Turn the key to run, and see if you have 12 volts. ) 0 volts still means bad or wrong relay. Did you check the resistance on the relay?

Reply to
Thomas Moats

It is the part that is mounted to the side of the distributor. You do not need a "special" tool to remove, just a "slightly" modified deep 1/4 socket. Yes it does require dielectric grease or "special goop".

Lets go over the very basics of DC electronics. A completed circuit has its power, ( the 12 volts you are looking at on the red wire ) the load ( the coil in the relay ) and ground ( the tan wire ). When you apply power but have no ground, source voltage ( the 12 volts you see on the red wire ) will be seen on the whole circuit up to where the open is. ( an open is like a broken wire ). If that "broken" wire is made to touch ground you now have a complete circuit, so the ground wire will now show 0 volts.

Now to the scenario you are having with what you are seeing on your car. As I told you before, when you turn the key to run, the ECM grounds the relay for a very brief time then takes the ground away. So you should see 12 volts except for the very brief moment in time that the circuit is grounded. What does your problem imply? An open relay. The tan wire is broken at the terminal in the relay socket. The ECM is always providing ground keeping the relay on. Now, the car does not run. So that would imply that; 1 you do not have fuel pressure; 2 the ECM does not see a crank signal. Now you stated that it does run on either. I think you also stated that if you jumper the yellow and orange wire the car does run. So that eliminates the ECM keeping the relay on by always grounding the relay. It also eliminates that the ECM is not getting a crank signal, so the ignition module is ok ( running engine ). What is left? A broken wire/terminal ( tan wire ) at the relay socket or bad relay. Want to do a down and dirty test on the relay socket? Make a test lamp. and with the relay removed use the test lamp to jumper the red wire and tan wire. Does it light when the key is in run, does it light when you turn the key to crank. If it is always lit with the key in run, a ground is being made. If it lights for a very brief time when you turn the key to run, normal.

Reply to
Thomas Moats

LOL! I give you and Thomas a lot of credit for sticking this one out as long as you have, but I think you may have finally met your match. Good luck... You're gonna need it. Ford builds a pretty bulletproof PCM, I guess we'll find out how good they protected the injector drivers... or not. Bob

Reply to
Bob

Agree, 100%

Bit of a paradox, no? She's been wanting to suspect the processor from the beginning, now we may never know...

Reply to
Neil Nelson

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.