Re: Auto Shutdown Relay......
[Re: Jim_Lusk]
#1120164
11/24/11 07:16 PM
11/24/11 07:16 PM
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Joined: Jan 2004
Posts: 27,347 Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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Have you tried grounding the circuit to energize the relay just to see if it'll fire up? I would..
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Auto Shutdown Relay......
[Re: moretoys]
#1120166
11/25/11 02:38 AM
11/25/11 02:38 AM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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"moretoys" is right that you should have two 12 volt sources at the shutdown relay. One hot all the time and the other will be hot with the key on as was stated. The PCM will turn the ASD and the fuel pump relay on for about a second when the key is turned on. It will work both the ASD and Fuel pump relays as they share the same ground provided by the PCM. You can see if look at the wire diagrahm and see that the ASD and fuel pump relay ground wires splice together and go to one pin at the PCM. The PCM must see the Crank sensor and Cam sensor signals to turn the ASD on and keep it on once the eng is cranked. A scanner really makes this so much easier as you can have the scanner comand the PCM to turn the relays on to test them but without a scanner you have to do it the hard way. You can check for power at the injectors while you crank to see if the relay is working. But if its not then you will need to check the basic componets that cause the ASD relay to turn on like the crank and cam sensors. I like to moniter the ground circuit for the ASD and fuel pump relays. You can just use a digital voltmeter and tap into the asd ground. When you crank the eng it should go to right about zero volts but if it stays near 12 volts then the PCM is not grounding the relay. You could even have somone ground the asd ground for a second while cranking to see what it does. I have done this before but was using a scanner as it told me more info when I supplied the ground myself to se what it did. Some engines will start without a cam sensor signal if the eng is cranked long enough. The PCM will start trying different fireing orders to work the injectors if it does not see the cam sensor but all else works. But you need to see just what the ASD is doing. Thats why if you tap a voltmeter into the ASD ground that the PCM supplies you can watch the volts. When you turn the key on the volts should go to 0 for a second and then to 12 as that is the relay turning off. Then when you crank it should go to 0 if the ASD relay turns on. If it stays at 12 while cranking then you have to figure out why the PCM is not grounding it. Do you have any scanner at all to use while you are working on it. Ron
Last edited by 383man; 11/25/11 02:40 AM.
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Re: Auto Shutdown Relay......
[Re: Jim_Lusk]
#1120168
11/25/11 02:55 AM
11/25/11 02:55 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Yes, I have both 12v sources. The PCM is not providing the ground for any length of time. I am going to substitute a '96 PCM (I've aleady confirmed the important connections are the same - a couple of the 2000 circuits are not in the PCM, but they don't appear to be important for the test) just to see if I get the ASR and fuel pump, maybe start it. I also need to make sure that the ground pins in the connector to the PCM are making contact. That would kill everything, but considering that I also have a "no bus" condition and no communication with the scan tool I figure the PCM is bad.
The relay will ONLY come on for 3 seconds while NOT cranking... it has to see the dist/firing input to keep it engaged
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Re: Auto Shutdown Relay......
[Re: Devilbrad]
#1120172
11/25/11 07:02 PM
11/25/11 07:02 PM
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Joined: Mar 2003
Posts: 18,678 Fresno, CA
Jim_Lusk
OP
I Live Here
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OP
I Live Here
Joined: Mar 2003
Posts: 18,678
Fresno, CA
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Quote:
Jim, I have seen this problem on several different Dakotas. It's always been a shorted out o2 sensor. PCM sees the short and shuts down the ASD relay. I would start by disconnecting the o2 sensors. And please dont fry my 96 PCM, I will need it back someday.
I wsa also thinking about yours the other day. Maybe I'll send it back with my son on Sunday as he lives real close to Stu now.
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Re: Auto Shutdown Relay......
[Re: Jim_Lusk]
#1120173
11/26/11 10:35 AM
11/26/11 10:35 AM
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Joined: Mar 2005
Posts: 2,489 Pacifica, CA
Devilbrad
top fuel
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top fuel
Joined: Mar 2005
Posts: 2,489
Pacifica, CA
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Quote:
Quote:
Jim, I have seen this problem on several different Dakotas. It's always been a shorted out o2 sensor. PCM sees the short and shuts down the ASD relay. I would start by disconnecting the o2 sensors. And please dont fry my 96 PCM, I will need it back someday.
I wsa also thinking about yours the other day. Maybe I'll send it back with my son on Sunday as he lives real close to Stu now.
Where does he live? Maybe him and I can meet some where. I have to run out to Lafayette around noon.
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Re: Auto Shutdown Relay......
[Re: Jim_Lusk]
#1120175
11/26/11 12:32 PM
11/26/11 12:32 PM
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Joined: Mar 2005
Posts: 2,489 Pacifica, CA
Devilbrad
top fuel
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top fuel
Joined: Mar 2005
Posts: 2,489
Pacifica, CA
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Quote:
Brad, he lives in the trailer park at the end of Hickey at El Camino. Like I said, I've got two here. I believe yours is the one that has writing on it, but I may just send both with him and you can confirm (or let me know the part number if you've got it).
He's about half way between Stu and I. Let me dig up the part number.
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