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Dead PCM?

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Old Aug 23, 2020 | 06:53 PM
  #51  
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That just means the wire is complete. You need to find which section also has continuity to ground. That's the wire you need to follow and find the short. (it might be right at either of the connectors.....)
 
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Old Aug 23, 2020 | 07:07 PM
  #52  
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Originally Posted by HeyYou
That just means the wire is complete. You need to find which section also has continuity to ground. That's the wire you need to follow and find the short. (it might be right at either of the connectors.....)
ok I typed the wrong PIN number above I meant pin 86 which is the brown and white wire. (I edited my post to reflect this)

if I go from pin 85 to the battery ground terminal I get 9.4ohms (your saying this should also be infinite correct?)

The wire going to pin85 is lime green with a black stripe and I should be tracing this wire back now correct?
alldata shows this wire as being “B28 output shaft speed sensor” with everything plugged in I get no reading to the b28 pin from the pin85 at the PDC
...(I think we’re making some progress here )

Sorry for being so dumb you are a hero for putting up with me.



 

Last edited by Packwood Digital; Aug 23, 2020 at 07:14 PM.
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Old Aug 23, 2020 | 07:36 PM
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Light Green/black stripe is the power feed wire for the relay control circuit. That one is working properly, as the fuel pump runs.
 
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Old Aug 23, 2020 | 07:42 PM
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Originally Posted by HeyYou
Light Green/black stripe is the power feed wire for the relay control circuit. That one is working properly, as the fuel pump runs.
so what should that one show with a multimeter?

theres 3 light green with black stripe wires coming from my PDC the fuel relay the ac clutch relay and and ASD relay

There is a black with green stripe going to my output speed shaft sensor

there is a lime green with black stripe going to a2 which is fused ignition switch

and a lime green going to b28
 

Last edited by Packwood Digital; Aug 23, 2020 at 07:50 PM.
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Old Aug 23, 2020 | 07:49 PM
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Yep, that wire feeds control side of the relays for a whole bunch of 'em. We don't care about that wire. It supplies power when it is supposed to, so, it is apparently fine. It's the side of the circuit from the relay, to the PCM that is what is giving you problems. Don't go lookin' for problems you don't have.

So, test from pin 85 to ground, with the other two connectors disconnected. (PCM, and the one in the cowl.) See what ya get. Should be no continuity to ground. Then, test from the connector in the cowl, (PCM side of the circuit) to ground. See what ya get. The one that shows low resistance is the wire that is causing the problem.....

And, just so we don't get way too far into this, and discover it's a bad relay.... Swap the fuel pump relay with another one. See if you get the same behavior. (probably shoulda checked that first...... but, I still ain't feelin' so hot, so, not thinkin' as clearly as I should..... )
 
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Old Aug 23, 2020 | 07:55 PM
  #56  
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Originally Posted by HeyYou
Yep, that wire feeds control side of the relays for a whole bunch of 'em. We don't care about that wire. It supplies power when it is supposed to, so, it is apparently fine. It's the side of the circuit from the relay, to the PCM that is what is giving you problems. Don't go lookin' for problems you don't have.

So, test from pin 85 to ground, with the other two connectors disconnected. (PCM, and the one in the cowl.) See what ya get. Should be no continuity to ground. Then, test from the connector in the cowl, (PCM side of the circuit) to ground. See what ya get. The one that shows low resistance is the wire that is causing the problem.....

And, just so we don't get way too far into this, and discover it's a bad relay.... Swap the fuel pump relay with another one. See if you get the same behavior. (probably shoulda checked that first...... but, I still ain't feelin' so hot, so, not thinkin' as clearly as I should..... )
pin 85 to the battery ground shows 9.5 ohms. Testing the rest now
if I swap the horn relay to the fuel pump it does the same just stays priming until I turn key off
 

Last edited by Packwood Digital; Aug 23, 2020 at 08:00 PM.
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Old Aug 23, 2020 | 07:57 PM
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That would indicate that wire has a short to ground somewhere. Hopefully the other wire does not......
 
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Old Aug 23, 2020 | 08:01 PM
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Originally Posted by HeyYou
That would indicate that wire has a short to ground somewhere. Hopefully the other wire does not......
so do I need to trace the green with black stripe wire like I did the other one?

Right before my CEL stopped lighting up and my scanner stopped working it showed code p1389 which is no ground to ASD right?
 

Last edited by Packwood Digital; Aug 23, 2020 at 08:05 PM.
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Old Aug 23, 2020 | 08:05 PM
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Nope. We don't care about the green wire.

The brown wire from the socket in the PDC seems to be where the problem is. Check the connector at the other end of that segment, make sure none of the wires are showing any bare copper..... If that looks ok, trace the wire end to end. Gotta be something in there somewhere.
 
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Old Aug 23, 2020 | 08:10 PM
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Originally Posted by HeyYou
Nope. We don't care about the green wire.

The brown wire from the socket in the PDC seems to be where the problem is. Check the connector at the other end of that segment, make sure none of the wires are showing any bare copper..... If that looks ok, trace the wire end to end. Gotta be something in there somewhere.
the brown wire with white stripe? Pin 19? That’s the one that shows .3ohms across the board from every connection from pdc to connector at cowl, from connector at cowl to pcm and from pin86 to pin19...

ive ripped out all the tape and wire channels and traced that wire 4 times end to end there is zero visible signs of damage. But I’ll do it again right now

I think my brain is getting overloaded.

Right before my CEL stopped lighting up and my scanner stopped working it showed code p1389 which is no ground to ASD right?
 
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