This is topic Brought it to my trusted shop and They don't know whats going on in forum Tech Talk at Northern California Ford Owners  .


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Posted by ddarkslayer (Member # 10688) on :
 
so I was told by the mechanic that he cannot communicate with the PCM. Did anybody have this problem or have any experience with it? I was told It comes down to me getting a 60 pin breakout box I looked it up and it looks like its just getting voltage from each pin. I don't know how to use one of those and are they expensive? My next step is that I'm going to change the engine harness. What do you guys think?
 
Posted by LXjames (Member # 10791) on :
 
What are you talking about? All I know is that your mechanic said something isn't working. What car are you speaking of what year what engine and tranny also might be helpful to know what PCM we are dealing with. And do you have any mods like a tune?
 
Posted by dohc90lx (Member # 11863) on :
 
yea im a tech at a dealer and when you cant communicate with the pcm we have to use the break out box. basically it allows you to read the pcm data streme live thru the pins coming into and out of the pcm. then you can isolate the problem from there. best bet, while expencive is take it to the dealer. they will be able to isolate the problem faster and more effectivly than a small shop that just plain dosent have the resources or equiptment than a dealer does. good luck with whatever problem you have!
 
Posted by 93PONY (Member # 60) on :
 
I've got a breakout box for sale if interested.
We no longer work on the older Fords so I have no use for the box.
 
Posted by phildog (Member # 1214) on :
 
My 2000 ranger would not communicate with the scanner, replaced the blown fuse and voila- scanned no problem. Don't know how long the fuse was blown because no other functions were affected.

Double check your fuses. It could be a really simple fix.
 
Posted by Duncan Motors (Member # 7045) on :
 
wut phil lsaid!!!!!!
 
Posted by Venomousnotch (Member # 8695) on :
 
quote:
Originally posted by Duncan Motors:
wut phil lsaid!!!!!!
+1 What Phildog said!!!!! [patriot] [patriot]
 
Posted by ddarkslayer (Member # 10688) on :
 
sorry fellas Its an 88 mustang with an EEC-IV processor I just bought a breakout box, I have an Idea on how to use it but I wouldn't know where to start looking. I know the name of the pin numbers but I dont know what I would know what to expect voltage wise on some pins
 
Posted by ddarkslayer (Member # 10688) on :
 
My original problem is that the PCM would tell the IAC to open up all the way idling at 3g sometimes. When the motor warms up after a short drive I would turn the car off and the engine would flood and the car would be hard to start even though the starter is cranking normally
 
Posted by 93 twintrbo (Member # 10475) on :
 
Did you check the voltage to the Iac valve when it acted up? From what I have seen on the ford Iac valves it has a middle range "park" position. The pcm needs to add voltage to the iac valve to "command" it open. If your car is idling at 3k rpm, the Iac would have to be pretty much maxed out voltage wise. Sometimes the iac pintle gets gummed up and sticks. If this were to happen and the PCM wanted to raise the idle to correct for a low idle, it would apply voltage to the iac valve. If it applied enough voltage to overcome the stuck position it then would idle very high.

It is possible that it was sticking at max "step". An stuck open Iac valve can cause hard starting.

Lawrence
 
Posted by ddarkslayer (Member # 10688) on :
 
When it idles that high I unplug the IAC and the RPM drops back down to 600 RPM. That being said it makes sense. My Idle air control is somewhat new but I will take a look at it.
 
Posted by 93 twintrbo (Member # 10475) on :
 
Yeah, the ford Iac valve has a spring inside that will pull the pintle to the base setting.
 
Posted by ddarkslayer (Member # 10688) on :
 
I would think maybe the spring is broken but if it wasnt the car wouldnt idle at 600 when I unplugged it.What kind of reading am I looking for when the IAC is maxxed out?
 
Posted by dohc90lx (Member # 11863) on :
 
i cant remember without looking it up what the iac voltage should be but check it at the break out box when it is doing it. there is a posability that you have a short to power on this pin that is intermitent and that would cause the condition. also the pcm may be commanding the voltage up on the iac because of a input from another sensor such as a maf. or map sensor, shorted tp or coolant temp sensor. all of those are major inputs for the pcm and it will command the output of the iac from there.
 
Posted by ddarkslayer (Member # 10688) on :
 
okay I will start a new thread when I get my breakout box
 




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