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What is "ASD" relay for?

"Auto Shutdown Relay". It powers up the fuel pump and fuel injection components indirectly. When you turn the key on, the PCM energizes the ASD briefly to provide a fuel system prime. After that it turns off until the PCM has a good crank signal. Then the PCM keeps it energized as long as there is a crank signal.
 
dothedew24_7 said:
This has possibilites
Friend: What's wrong with my truck Jay?!?
Me: I dunno- it was workin fine a few minutes ago :D
Click to expand...


how bout i give you...oh say $500.00 for it since its not running ?
 
Here's a cool way to make the ASD relay work more for you as an anti-theft device. Credit goes to Lunghd for THIS LINK

Ivan
 
Ivan said:
Here's a cool way to make the ASD relay work more for you as an anti-theft device. Credit goes to Lunghd for THIS LINK

Ivan
Click to expand...
Thanks Ivan. That got bookmarked. BTW that trick will work on any fuel injected Chrysler that Iv'e seen.
 
Re: What is "ASD" relay for? -- Need help diagnosing ASD relay problem!

Well, she's staying where she's parked until I can figure out what's going on. I've got no spark and no fuel injector pulse. I've got no voltage on the coil input (primary) connections. I just hooked up my Autotap scan tool to it, and it gives me two codes:

P1388 - Auto shutdown relay control circuit -- an open or shorted condition detected in the ASD or CNG shutoff relay control circuit

P1389 - No ASD relay output voltage at PCM -- (a) No Z1 or Z2 voltage sensed when the auto shutdown relay is engergized, (b) An open circuit detected in the ASD relay output circuit

I verified that the relay itself is working properly -- if I apply 12 volts to the coil side, the switch closes and has nearly zero resistance. Where the ASD relay plugs into the Power Distribution Center, I verified that one side of the relay's coil IS receiving 12 volts when the ignition is in the "run" position (in other words, the PCM is trying to close the relay). But, with the ignition in the "run" position, I get ZERO volts on either of the two switched terminals. Shouldn't I have 12V on one side or the other of the switch when the ignition is in the "run" position?

Thanks in advance!
 
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Re: What is "ASD" relay for? -- Need help diagnosing ASD relay problem!

Yes it should have one hot all the time even with the key off. I would check for a blown fuse, a bad conection, cut wire, or melted fuseable link[I don't think xj's used them though].
 
I checked, and the 20A fuse in the kick panel which supplies power to the switched side of the ASD relay is OK. One thing that seemed strange -- with the fuse removed, I checked the power on each side of the fuse terminal. I expected to see one side having ZERO volts and one side having 12 volts. Oddly enough, one side had 12 volts, but the other side had 2 volts. I wonder if that should be pointing me to something?
 
The ASD supplies battery voltage to the fuel injectors, ignition coil and oxygen (O2S) sensor heating elements. The ground circuit for the coil in the ASD relay is controlled by the powertrain control module (PCM) The PCM operates the relay by switching the ground circuit on and off.

OPERATION
Terminal number 30 is connected to battery voltage. For both the ASD and fuel pump relays, terminal 30 is connected to battery voltage at all times.
The PCM grounds the coil side of the relay through terminal number 85.
Terminal number 86 supplies voltage to the coil side of the relay.
When the PCM de-energizes the ASD and fuel pump relays, terminal number 87A connects to terminal 30. This is the Off position. In the off position, voltage is not supplied to the rest of the circuit. Terminal 87A is the center terminal on the relay.
When the PCM energizes the ASD and fuel pump relays, terminal 87 connects to terminal 30. This is the On position. Terminal 87 supplies voltage to the rest of the circuit.

There are three fuses to check depending on year. A 25A, 20A, and 15A which are shown in the underhood fusebox. What year is it?
 
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The ASD Relay is activated only for a few seconds when you turn the key to "run", and then activates and holds later when the PCM sees the CPS signal..... if it does.
So, How's your CPS?


EDIT: Oooops. Forgot you already pulled the codes. Disregard this.
 
MJR said:
The ASD supplies battery voltage to the fuel injectors, ignition coil and oxygen (O2S) sensor heating elements.

There are three fuses to check depending on year. A 25A, 20A, and 15A which are shown in the underhood fusebox. What year is it?
Click to expand...

The ASD relay is making more sense all the time as the culprit, because I'm measuring ZERO volts at the ignition coil primaries. Now, if I can just figure out why I don't have power to the switch side of the relay...

Just a side thought -- Could I safely supply 12V from some other source to the ASD relay switch terminals (in effect bypassing the relay circuit) just to verify that this is my problem?
 
Even if you turn on the ASD relay the PCM won't switch the coil if it is not turning on the ASD relay. What year is yours?
 
Doh! Anyway the ASD relay is powered by fuse #19 which is 25A in the underhood fusebox. The output power then goes to two fuses also in the underhood fusebox. One is #21 a 20A fuse going to the fuel injectors, coil, and PCM. The other is #24 a 15A for the O2 sensor heaters. Also the ASD coil side is power with the key on through #11 a 20A fuse in the inside fusebox.

If you have power on two of the pins with the key on and the relay removed then chances are the PCM isn't turning the relay on. I'd reconnect everything and try a battery disconnect to reset the PCM to see if it will start then. Some codes can be triggered by unplugging stuff with the key on.
 
I had a similar (in respect to the codes) problem in my TJ. The problem was an intermittent circuit feeding ASD voltage to the PCM. When diagnosing, I could verify voltage at various feeds from the ASD, but the PCM was not getting a signal and therefore would not power up other components. If I gave the PCM 12 volts at the ASD sense pin, everything worked fine. Symptoms were intermittent stalling or no start. The problem was a splice where the ASD voltage split and moving that section of the harness usually made it work temporarily.
 
explorer said:
I had a similar (in respect to the codes) problem in my TJ. The problem was an intermittent circuit feeding ASD voltage to the PCM. When diagnosing, I could verify voltage at various feeds from the ASD, but the PCM was not getting a signal and therefore would not power up other components. If I gave the PCM 12 volts at the ASD sense pin, everything worked fine. Symptoms were intermittent stalling or no start. The problem was a splice where the ASD voltage split and moving that section of the harness usually made it work temporarily.
Click to expand...

I would be careful on jumpering any wires leading to the 96-up PCM's as you can blow out a driver on the board.
 
MJR said:
I would be careful on jumpering any wires leading to the 96-up PCM's as you can blow out a driver on the board.
Click to expand...

Key off, send 12 volts to the ASD sense by splicing around the suspected problem area. Then key on. What could this harm? I worked on Jeeps for 8yrs. and while I didn't consider myself an electrical specialist I think that is a safe and proper method of finding the problem. What am I missing? And what changed after 96 that would change your advice?
 
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