Scanner won't communicate with computer
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Freshman User
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I appreciate the diagram. I'm not the most technical sound person when it comes to testing electrical stuff. Any way anybody could walk me through how to test these pins?
Do I just hook up a multimeter and set it ohms and ground and test the Resistance of each pin hole ? Or just a test light if the pins are gettin power?
Do I just hook up a multimeter and set it ohms and ground and test the Resistance of each pin hole ? Or just a test light if the pins are gettin power?
Elder User
Joined: Aug 2015
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To see if it has power test the 16 pin. On that diagram it is the one coming from the relay that says F Series. You can use your test light, clipped to a ground, touch the probe to the 16 pin on the usb port. You can tell which one by the diagram and shape and count. With key on, if it lights up, then your usb port has power. THe other pins are ohm tested, one probe on the usb pin your testing, the other probe on the corresponding pin on the PCM plug. If you touch the two probes together before hand, the reading is the same reading you want when you test. If it shows a number, it has resistance and theres a problem with that wire. SO again your looking for the same reading as when you just touch the two probes on the multimeter set to ohms together. What it does is send a signal down the wire from one probe to the other. If not all of the signal makes it, that's resistance, the number is how much resistance. If the wire is good and all the signal makes it then there is no resistance and good to go. Now if all the pins test good. Then you probably have an issue with the stuff you bought, not the truck.
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Freshman User
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To see if it has power test the 16 pin. On that diagram it is the one coming from the relay that says F Series. You can use your test light, clipped to a ground, touch the probe to the 16 pin on the usb port. You can tell which one by the diagram and shape and count. With key on, if it lights up, then your usb port has power. THe other pins are ohm tested, one probe on the usb pin your testing, the other probe on the corresponding pin on the PCM plug. If you touch the two probes together before hand, the reading is the same reading you want when you test. If it shows a number, it has resistance and theres a problem with that wire. SO again your looking for the same reading as when you just touch the two probes on the multimeter set to ohms together. What it does is send a signal down the wire from one probe to the other. If not all of the signal makes it, that's resistance, the number is how much resistance. If the wire is good and all the signal makes it then there is no resistance and good to go. Now if all the pins test good. Then you probably have an issue with the stuff you bought, not the truck.
Do do the other ones I set it to 20 ohms.
Touch the two wires together and that's the resistance I should be checking for?
Then ground the black and test the rest of the pins and the reading I get should be the same as to when I touched the two mutimeter wires together ?
Am I doing this correct
Elder User
Joined: Aug 2015
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Haha. 20ohms is fine. Pin 16 is the only one you use the test light on. Test light clipped to a ground on the vehicle. Then probe pin 16 with the key on. The test light should light. The rest are the ohm test. Using the multimeter set to 20ohms. Multimeter has two probes, red, black, or positive negative. One goes on the pin you want to test on the usb port. The other goes on the corresponding pin on the PCM plug. That's the 104pin plug under the hood that goes threw the fire wall with a bolt in the middle. You need a wire diagram so you know which pin corresponds to the pin on the usb port. Basically there is a wire for each pin on that usb plug. All those wires go to the pcm . So you are just testing both ends of the same wire to see if its broken. I'm not a teacher sorry. Best I can explain.
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Freshman User
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Okay guys sorry to get back so late. I work nights so not much gets done on those days . But, anyway I'm run you guys through what I did let me know if I messed up.
Tested pin 16 with test light and key on got power to light so that pin is good.
The rest are ohm tested got that. So I set the multi meter to 20 ohms grounded the black wire on a metal wrench so I have a good ground. Next put the red lead in each of the pins. Key off. Do I need to disconnect the battery ?Did I do this right ?
Now here where it got weird.
Once I did that I got readings all over the place in each pin. From 10-16. I must of messed this up at some point cause that doesn't sound right ?
Thank y'all
Tested pin 16 with test light and key on got power to light so that pin is good.
The rest are ohm tested got that. So I set the multi meter to 20 ohms grounded the black wire on a metal wrench so I have a good ground. Next put the red lead in each of the pins. Key off. Do I need to disconnect the battery ?Did I do this right ?
Now here where it got weird.
Once I did that I got readings all over the place in each pin. From 10-16. I must of messed this up at some point cause that doesn't sound right ?
Thank y'all
FTE-Spread The Knowledge
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If you pull that cigar/OBDII fuse I think that would be fine when checking resistance. But some here will recommend disconnecting the batteries because you are dealing with the brain of the truck.
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Freshman User
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Okay I'll check again the In the AM with the battery disconnected.
Is that correct sequence for checking the resistance?
Also, if those the readings for those pins does that mean the computer plug for the truck is shot ?
Is that correct sequence for checking the resistance?
Also, if those the readings for those pins does that mean the computer plug for the truck is shot ?
Elder User
Joined: Aug 2015
Posts: 535
Likes: 3
When ohm testing your not grounding one of the leads. One lead goes on the pin your testing, the other lead goes on the PCM plug pin that corresponds to the pin you are testing on the Port. Once again. THe pin on the port has a wire going to the other pin on the PCM plug. So no grounding to a wrench. ONe lead on each pin. Since you have power to the 16 pin. And your truck is fine. I'd say your having a hardware issue with your scanner. Have you tried some one with AE to see if that works. If your truck is not fine, I can't remember that far back, then you should have tried my original suggestion for a dead sensor. Lol. I'm following a lot of posts. Cant remember.
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