Random no start
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New User
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Awesome. How do you recommend to test at the harness? I tried to back probe the pcm harness yesterday, but wasn't very successful because how packed in all the wires are. I was thinking of getting a short piece of stainless .020 safety wire from work and plugging it in the front then just clipping onto it
Fleet Owner
Joined: Nov 2003
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If you are going to back-probe, I would only do it if you had the correct back-probe pin.
Also, I would recommend extreme caution just taking a steel wire and inserting it in the connector. I don't know the pin sizes and wouldn't want you to damage or even loosen connections on, the PCM plug.
Here is the back-probe pin I use:
https://www.ford-trucks.com/g/picture/9417565
https://www.ford-trucks.com/g/picture/9417576
Also, I would recommend extreme caution just taking a steel wire and inserting it in the connector. I don't know the pin sizes and wouldn't want you to damage or even loosen connections on, the PCM plug.
Here is the back-probe pin I use:
https://www.ford-trucks.com/g/picture/9417565
https://www.ford-trucks.com/g/picture/9417576
Hotshot
Joined: Dec 2003
Posts: 15,369
Likes: 121
From: Stuttgart, Ar
I would have guessed it was an 04 (after 9/29) motor by the thread title. I never could find out what was wrong with my old harness after I had it out, I just got tired of the random no start for no reason issue. I think my harness was under $300.00 when I changed it and the later 04 was about 600. Crazy and very frustrating. Never had an issue since (knock on wood).
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Thanks for all the great info and resources guys!
One more question on the buzz test though.... have you ever had the buzz test start, then intermittently stop and start? That's the other strange to me symptom that I've seen with this truck. That's why I was asking what commands the buzz test... seems like a possible bad ground or something to whatever makes it happen...
One more question on the buzz test though.... have you ever had the buzz test start, then intermittently stop and start? That's the other strange to me symptom that I've seen with this truck. That's why I was asking what commands the buzz test... seems like a possible bad ground or something to whatever makes it happen...
Fleet Mechanic
Joined: Jul 2018
Posts: 1,629
Likes: 103
From: Jacksonville Florida
Hey good Morning Drinker.
Listen if you read a lot of posts on here you have herd of forscan. It's fairly cheap.
$4.99 app for your cell phone. If ya have an Android you'll need a elm327 Bluetooth dongle, if ya have an apple phone you'll need an elm327 Wi-Fi dongle. 30 bucks I believe. Now you can get the full version for Windows for free but you have to buy the USB cable to connect.
Point is this program or app can do buzz tests and has really strong code reading abilities. I would look into it or something similar.
Listen if you read a lot of posts on here you have herd of forscan. It's fairly cheap.
$4.99 app for your cell phone. If ya have an Android you'll need a elm327 Bluetooth dongle, if ya have an apple phone you'll need an elm327 Wi-Fi dongle. 30 bucks I believe. Now you can get the full version for Windows for free but you have to buy the USB cable to connect.
Point is this program or app can do buzz tests and has really strong code reading abilities. I would look into it or something similar.
Fleet Mechanic
Joined: Jul 2018
Posts: 1,629
Likes: 103
From: Jacksonville Florida
Mark.
Mine doesn't do the buzz test when I turn key on. All I get is fuel pump. And it runs great.
I can do a buzz test with forscan and all was good last time I did one. I have an economy tune on it for mileage but it still runs like a Bat out of He--.
Mine doesn't do the buzz test when I turn key on. All I get is fuel pump. And it runs great.
I can do a buzz test with forscan and all was good last time I did one. I have an economy tune on it for mileage but it still runs like a Bat out of He--.
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Thread Starter
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New User
Joined: Oct 2019
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Hey good Morning Drinker.
Listen if you read a lot of posts on here you have herd of forscan. It's fairly cheap.
$4.99 app for your cell phone. If ya have an Android you'll need a elm327 Bluetooth dongle, if ya have an apple phone you'll need an elm327 Wi-Fi dongle. 30 bucks I believe. Now you can get the full version for Windows for free but you have to buy the USB cable to connect.
Point is this program or app can do buzz tests and has really strong code reading abilities. I would look into it or something similar.
Listen if you read a lot of posts on here you have herd of forscan. It's fairly cheap.
$4.99 app for your cell phone. If ya have an Android you'll need a elm327 Bluetooth dongle, if ya have an apple phone you'll need an elm327 Wi-Fi dongle. 30 bucks I believe. Now you can get the full version for Windows for free but you have to buy the USB cable to connect.
Point is this program or app can do buzz tests and has really strong code reading abilities. I would look into it or something similar.
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I was able to do a couple of tests on my cam and crank circuits from the pcm connector.... my cam tested to 850 ohms, which is awesome. My crank tested to slightly above 400 ohms.... so slightly out of the 300-400 listed range. I then measured Pin E30(CKP+) and E41(CKP-) to ground and had no reading.... then I did pin E30 to E42(GRD), and E41 to E42(GND) and got no reading.... for fun I tested E42 to Chassis ground, and got no reading.....
Shouldn't E42 show a connection to chassis ground?
Shouldn't E42 show a connection to chassis ground?
Fleet Owner
Joined: Nov 2003
Posts: 27,916
Likes: 3,635
I was able to do a couple of tests on my cam and crank circuits from the pcm connector.... my cam tested to 850 ohms, which is awesome. My crank tested to slightly above 400 ohms.... so slightly out of the 300-400 listed range. I then measured Pin E30(CKP+) and E41(CKP-) to ground and had no reading.... then I did pin E30 to E42(GRD), and E41 to E42(GND) and got no reading.... for fun I tested E42 to Chassis ground, and got no reading.....
Shouldn't E42 show a connection to chassis ground?
Shouldn't E42 show a connection to chassis ground?
With the PCM connector disconnected AND the CKP sensor disconnected, the resistance should be greater than 10,000 ohms between:
E30 and ground
E41 and ground
E30 and E42
E41 and E42
You posted that the CKP was new. I am not sure that if the resistance was only a little over the 400 ohm upper spec, that I would worry about it.
If you are looking to verify the PCM grounding circuit (E42), one thing to remember is that the PCM activates numerous circuits by applying the ground, some at key on, some when cranking IIRC. That said, electrical troubleshooting is not really my cup of tea beyond the real "basic" testing. I would imagine that the CKP ground would be applied by the PCM at KOEO.
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explorerdad
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Sep 5, 2001 06:39 PM