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Dead PCM?

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Old Aug 23, 2020 | 03:04 PM
  #31  
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Originally Posted by HeyYou
Normal. Voltage to pin 85 is supplied via the ignition switch. PCM controls ground side of the circuit.

Should be able to just unplug the connector, stick your probe into the appropriate hole, ground the other one, and see what you get. (ignition off.) Should be an open circuit. (leave the relay out too.)
zero resistance whatsoever
 
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Old Aug 23, 2020 | 03:06 PM
  #32  
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Then you have a short to ground on that wire. It might be under the PDC..... Gonna have to physically trace the wire end to end, and find the short.
 
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Old Aug 23, 2020 | 03:10 PM
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Originally Posted by HeyYou
Then you have a short to ground on that wire. It might be under the PDC..... Gonna have to physically trace the wire end to end, and find the short.
alrighty I’ll start over and report back shortly. Luckily I have nothing better to do today LoL.

its really hard to lift the PDC cause the wires under it I was afraid that if I did lift it too much I would ya k someThing out of place. But tha probably where it is.
 
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Old Aug 23, 2020 | 03:13 PM
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Originally Posted by Packwood Digital
zero resistance whatsoever
Please clarify: You have 0 ohms or you're not measuring anything ? Because earlier it measured 0.6 ohms to ground.
 
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Old Aug 23, 2020 | 03:16 PM
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Originally Posted by DerTruck
Please clarify: You have 0 ohms or you're not measuring anything ? Because earlier it measured 0.6 ohms to ground.
actually my ground on my
meter must have been loose or I had the wrong setting cause I just tried again and measure 86ohms consistently at pin 19

(my ohm meter dial is set to the lowest setting “200” if that makes a difference I had it on 200k earlier)
 

Last edited by Packwood Digital; Aug 23, 2020 at 03:18 PM.
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Old Aug 23, 2020 | 03:19 PM
  #36  
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Should be infinite..... Any resistance aside from some stupid high number is bad news.
 
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Old Aug 23, 2020 | 03:20 PM
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Originally Posted by Packwood Digital
actually my ground on my
meter must have been loose or I had the wrong setting cause I just tried again and measure 86ohms consistently at pin 19

(my ohm meter dial is set to the lowest setting “200” if that makes a difference I had it on 200k earlier)
Same on pin 85 at the fuel pump relay socket ?
 
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Old Aug 23, 2020 | 03:50 PM
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Originally Posted by DerTruck
Same on pin 85 at the fuel pump relay socket ?
if I go from battery ground to pin 85 at the pump relay socket it says 06.0 ohms on the same “200” meter setting
 
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Old Aug 23, 2020 | 03:51 PM
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Originally Posted by HeyYou
Should be infinite..... Any resistance aside from some stupid high number is bad news.
On the other pins from the pcm connector when I test them it give various readings from 13 to 85ish depending on the pin. and some don’t change from the initial 1 .
but the pin19 gives the 85 ohm consistently

so does that still confirm a short? Should only the pump relay give an infinite reading?
 

Last edited by Packwood Digital; Aug 23, 2020 at 03:56 PM.
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Old Aug 23, 2020 | 04:11 PM
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Hmm if you're measuring 0.6 ohms at pin 85 in the relay socket you should measure the same at the connector end of the wire. In any case 0.6 ohms at the relay socket with the connector disconnected at the PCM is clearly a short to ground somewhere.
 
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