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Old 12-14-2013, 04:46 PM   #1
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The Auto-Shutdown Relay:

Hey Guys,

1991 2.5 Ax-5:

Continuing my troubleshooting from another thread (Fuel Pump Not Priming:)
I wanted to know everything about the auto-shutdown relay in the relay control center under the hood.

What are the requirements to activate the relay? Does the relay tell the fuel-pump to shut off once the proper pressure is maintained? Without digging into the other thread, my problem is either:

1) Battery cable connected, fuel pump won't come on when key-on OR cranking.
2) Fuel pump won't shut off the instant the battery cable is connected, maintains 35 psi and Jeep will start and run, but when I key-off the fuel pump continues to run.

These 2 scenarios are dependent on which new "fuel pump relay" i have installed. I haven't messed with the "auto-shutdown" relay yet. Any information will help, I think I'm almost at the end of this month long troubleshooting process.

I found a relay test for a cherokee with the same issues, so I will try to ohm it out per that test. I just wanted to know if I'm even pointed in the right direction with the ASD relay, thanks.

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Old 12-14-2013, 07:48 PM   #2
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Here is the test I performed and the results:
1991 Jeep YJ 2.5L Ax-5 Fuel Pump Not Priming OR Running Continuously

Performed Check of Relays: Fuel Pump (F) Auto-Shutdown (ASD) and New Relay from AutoZone (NEW)
_________________________________________

1) With relay removed from tray, use an ohmmeter to check resistance between terminals 85 & 86, value should be 75 ohms + / - 5 ohms

New: 79 ohms
F: 1.6K ohms
ASD: 76 ohms

Results for step 1: Fuel Pump Relay did not pass the test.
__________________________________________

2) Connect the ohmmeter between terminals 30 and 87A, the meter should show continuity

New: Continuity
F: Continuity
ASD: Continuity

Results for step 2: All three relays showed continuity between the terminals 30 and 87A, test passed
__________________________________________

3) Connect the ohmmeter between terminals 87 and 30, there should be NO continuity at this time.

New: Continuity
F: Open Line
ASD: Open Line

Results for step 3: The New Relay from AutoZone did not pass this test, probable why fuel pump continuously runs when this relay is installed. Internal short suspect.
________________________________________

4A) Connect a jumper wire to relay terminal 85 position, connect opposite end to 12V ground source. Connect a jumper wire to relay terminal 86 position, connect opposite end to 12V power source. This activates the relay, a distinctive "click" can be heard or felt:

New: Activated
F: Activated
ASD: Activated

Results for step A4: All relays activated when supplied ground/power to terminals 85/86 respectively
_________________________________________

4B) While activated, the ohmmeter should NOW SHOW continuity between terminals 87 & 30

New: Continuity
F: Continuity
ASD: Continuity

Results for step 4B: All relays showed continuity while in the activated position
________________________________________

4C) While activated, the ohmmeter should show NOT SHOW continuity between terminals 87A and 30

New: Continuity
F: Open Line
ASD: Open Line

Results for step 4C: The New Relay did not pass the test
______________________________________________

Total Results:

New Fuel Pump Relay: Failed Test 3 and 4C
Original Fuel Pump Relay: Failed Test 1
Auto-Shutdown Relay: Passed All the Tests

Going to replace the fuel pump relay with a new one. Hopefully I can find one that doesn't look different and fits, this will be my 4th attempt. The ASD was reinstalled since it checked ok. Will get back with results again.

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Old 12-14-2013, 11:06 PM   #3
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Have you tried using the horn relay for the fuel pump relay, assuming your horn works? I believe they are all the same, at least they are in my 95 yj
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Old 12-14-2013, 11:24 PM   #4
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Quote:
Originally Posted by flkeysff View Post
Have you tried using the horn relay for the fuel pump relay, assuming your horn works? I believe they are all the same, at least they are in my 95 yj
I don't have a horn relay in the fuse box, I did try the starter relay but it didn't change anything, still not priming when I key-on or crank. I know that the relay is getting power to the box, it's just not sending it to the fuel pump when it needs to. I don't know what the requirements for priming the fuel pump are, still confused lol.

I definitely know that the pump "can" receive power and will charge to 35psi to start and maintain running the Jeep. That was with the faulty new AutoZone relay installed it was grounded out. So the pump definitely works, not sure why it's not getting power.

Do you think it has something to do with the ignition switch? How can I test the fuse box if the right terminal is getting power when I key-on?
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Old 12-15-2013, 12:28 AM   #5
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Wow. That sounds like a shitload of work to test a relay. Have to take some wire, wire either coil (85 or 86) to ground and carefully touch the other cool to 12v. If it clicks, it works. Ive never seen one burn out at the 30 coil. All it does is switch whatever polarity is wired to 30, to either 87 or 87a.

Then probe the coil wired at the harness. Both should read ground until you turn the ign to ign. One of those coils will turn to 12v. If that happens , make sure you have positive polarity at 30. That's all.

If all checks out, my guess is a bad sensor. Maybe crank sensor. Comp will kill fuel and spark if its toast. There are only like 3 basic components to the fuel system. And you've already eliminated 1. Next is ignition and last is there relay.
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Old 12-15-2013, 12:53 AM   #6
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Originally Posted by Jeeprich25 View Post
Wow. That sounds like a shitload of work to test a relay. Have to take some wire, wire either coil (85 or 86) to ground and carefully touch the other cool to 12v. If it clicks, it works. Ive never seen one burn out at the 30 coil. All it does is switch whatever polarity is wired to 30, to either 87 or 87a.

Then probe the coil wired at the harness. Both should read ground until you turn the ign to ign. One of those coils will turn to 12v. If that happens , make sure you have positive polarity at 30. That's all.

If all checks out, my guess is a bad sensor. Maybe crank sensor. Comp will kill fuel and spark if its toast. There are only like 3 basic components to the fuel system. And you've already eliminated 1. Next is ignition and last is there relay.
It actually wasn't that bad to test all three relays. It was just a step by step process to make sure that each component inside the relay works as advertised. They all clicked on, but the "new" relay wouldn't turn off, and the original one had waaaay too high low resistance between 85 & 86. The only one that passed all the checks was the auto-shutdown, which I figured was good anyway. The original and "new" fuel pump relay were bad as per that test. Will try to replace that tomorrow.

Can you explain what you mean by probing the harness like you said? And what you mean by coil wire? Like, a hot jumper wire?

Also, I know the ignition system is good. When the "new" relay was installed, it would continuously run the fuel pump. I was able to start my Jeep and it ran perfect. I was also able to get it to rev up and down like normal. However when I shut the engine off, the "new" relay would still keep the pump operating, (bc it was grounded internally per the test), even though it had 35psi at the rail, which is why I questioned the auto-shutdown relay, but that tested good. The crank&cam sensors are new too, replaced last year for inspection.

I am glad the "new" relay was actually bad because it showed me that the fuel pump works, there's no clog in the lines, the ignition system works, and that my problem is electrically-based. If you could explain exactly what you want me to do I'd really appreciate it. This is the first major electrical problem I've had with my Jeep so I need it dumbed down as much as possible lol.
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Old 12-15-2013, 01:57 PM   #7
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Quote:
Originally Posted by Defcon 1 View Post
I don't have a horn relay in the fuse box, I did try the starter relay but it didn't change anything, still not priming when I key-on or crank. I know that the relay is getting power to the box, it's just not sending it to the fuel pump when it needs to. I don't know what the requirements for priming the fuel pump are, still confused lol. I definitely know that the pump "can" receive power and will charge to 35psi to start and maintain running the Jeep. That was with the faulty new AutoZone relay installed it was grounded out. So the pump definitely works, not sure why it's not getting power. Do you think it has something to do with the ignition switch? How can I test the fuse box if the right terminal is getting power when I key-on?
I am fighting a similar issue and have done everything from changing the computer to the cps and everything in between. I do however get the fuel pump to prime and power to my coil when I turn my key on, I do not get power to them when I crank the engine. I am now going to replace my distributer sensor and see if that is my problem. But I do not think the ignition switch is at fault since you could get the fuel pump running with a bad relay. Have you checked the dome light fuse? I Read that this could affect some issues with the computer that could cause similar circumstances. Have you pulled the codes? If you don't have a scanner turn the key on and off two times and on the third on leave it the on and start counting the check engine light.
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Old 12-15-2013, 02:26 PM   #8
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Quote:
Originally Posted by flkeysff View Post

I am fighting a similar issue and have done everything from changing the computer to the cps and everything in between. I do however get the fuel pump to prime and power to my coil when I turn my key on, I do not get power to them when I crank the engine. I am now going to replace my distributer sensor and see if that is my problem. But I do not think the ignition switch is at fault since you could get the fuel pump running with a bad relay. Have you checked the dome light fuse? I Read that this could affect some issues with the computer that could cause similar circumstances. Have you pulled the codes? If you don't have a scanner turn the key on and off two times and on the third on leave it the on and start counting the check engine light.
Thank you I will do as you suggested. I did replace the Dome fuse, it wasn't bad, but I replaced it precautionary. I currently don't have a check engine light, but I will see if there are any faults. I never knew about checking codes that way lol, learn something everyday with a Jeep.

I originally was going to leave the bad relay in there and run a switch to the fuel pump ground, that way I could bypass the problem and actually use my Jeep. However I really feel the need to do this correctly and solve the problem for real.

I am preparing to make several small jumper wires that will come out of the fuse-box and elevate the fuel pump relay in mid air. That way I can tell which wire(s) receives power in whatever ignition position is on. If I can find a diagram of the circuitry, I can start eliminating portions of the circuit. I will try the code check first, thank you for the help.
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Old 12-15-2013, 02:48 PM   #9
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Quote:
Originally Posted by flkeysff View Post
I am fighting a similar issue and have done everything from changing the computer to the cps and everything in between. I do however get the fuel pump to prime and power to my coil when I turn my key on, I do not get power to them when I crank the engine. I am now going to replace my distributer sensor and see if that is my problem. But I do not think the ignition switch is at fault since you could get the fuel pump running with a bad relay. Have you checked the dome light fuse? I Read that this could affect some issues with the computer that could cause similar circumstances. Have you pulled the codes? If you don't have a scanner turn the key on and off two times and on the third on leave it the on and start counting the check engine light.
You could have a problem with the ignition switch...
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Old 12-15-2013, 02:49 PM   #10
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The ecm controls power to the fuel pump...you may have the infamous bad capacitors in the ecm...
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Old 12-15-2013, 05:44 PM   #11
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So there are 5 basic standard contacts in all relays. 85 and 86 are called the coils. One of those coils will be either positive or negative all the time. The other will become the opposite polarity when the key is turned on.

It sounds like the "new" relay was stuck closed. Which means the 30 contact was stuck to the 87 contact, providing power to the fuel pump all the time. Make sense?

I'd pull the relay and look under it at the prongs. Each will be numbered. Match those prongs up to where they plug in. You can then tell which wires going to the relay are the coil wires etc. make sure one of them is always on. And one is coming on (opposite polarity) with the key. If that works, and the wire going to the 30 prong has 12v? Your wiring is all good from the switch to the relay.

PM me if this is still confusing. Relays are super simple and a great place to troubleshoot much of the ignition system.
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Old 12-15-2013, 10:14 PM   #12
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Quote:
Originally Posted by Jeeprich25 View Post
So there are 5 basic standard contacts in all relays. 85 and 86 are called the coils. One of those coils will be either positive or negative all the time. The other will become the opposite polarity when the key is turned on.

It sounds like the "new" relay was stuck closed. Which means the 30 contact was stuck to the 87 contact, providing power to the fuel pump all the time. Make sense?

I'd pull the relay and look under it at the prongs. Each will be numbered. Match those prongs up to where they plug in. You can then tell which wires going to the relay are the coil wires etc. make sure one of them is always on. And one is coming on (opposite polarity) with the key. If that works, and the wire going to the 30 prong has 12v? Your wiring is all good from the switch to the relay.

PM me if this is still confusing. Relays are super simple and a great place to troubleshoot much of the ignition system.

Roger that, I will definitely look into this. Thanks for the help I will PM you if I run into a wall lol.



Quote:
Originally Posted by Garyk View Post
The ecm controls power to the fuel pump...you may have the infamous bad capacitors in the ecm...
hopefully not... lol. I'm hoping that since the pump does get power with the "new" (bad) relay installed, that the ECM is in fact sending power to the relay. Hopefully that portion of the circuit is good.




Here is a basic schematic someone posted a long time ago for the 91' Wrangler. I'm not sure if its for the 2.5L, but I will try to troubleshoot it per this. Does anyone disagree or think the drawing is inaccurate?

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