DLC connection issue
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
DLC connection issue
As the title says, I am having an issue with my DLC connection. I just loaded a Looney Economy tune into my truck and that went fine. However, when I plug in my ELM327 to run my monitors the truck sputters and dies. If I unplug the Elm before it dies it will start to run fine again. Does anyone have any ideas on where to even start looking. I cannot even pull codes to help.
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
I tried a different scanner and my SCT X4 tuner. Nothing in communicating. How ever the truck does run. An odd thing I noticed, no matter what is plugged in, the engine icon on the cluster flashes, there is a clicking sounding like the flasher relay and the dome light dims with the flashes. As soon as I remove what ever is plugged in all returns to normal. I did check the B+ pin 16 with the body ground pin 4 and sensor ground pin 5. Both pins so about 12.5v on the multi meter.
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
Does anyone have a better wiring diagram for the DLC I looked at the 2005 Bible and figured out were all but 2 of the wires go. The orange wire in Pin 3 and the blue with white stripe wire in pin 7.
I am wondering if there is something on the CAN like a relay or something, up by the cluster, that is where the sound seem to be coming from.
I am wondering if there is something on the CAN like a relay or something, up by the cluster, that is where the sound seem to be coming from.
Lead Driver
Joined: Dec 2006
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From: So. Jersey
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Fleet Owner
Joined: Nov 2003
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Verify 5 volts for v-reference voltage at pin #10.
Verify 3.5 volts at pin #7. Not sure why on this one, but it is in the procedure!
Check for v-reference short by unplugging the two wire sensors and testing:
EOT, ECT, IAT1 (MAT at the MAF, IAT2, TFT, WIF sensor. Also the ambient air temp and cab air temp through the HEC).
Check for v-reference short by unplugging the three wire sensors and testing:
Fan speed sensor (in fan clutch connector wiring), APP, EGR valve, ICP, EBP, MAP, BARO, TPS sensors, vehicle speed sensor.
Verify 3.5 volts at pin #7. Not sure why on this one, but it is in the procedure!
Check for v-reference short by unplugging the two wire sensors and testing:
EOT, ECT, IAT1 (MAT at the MAF, IAT2, TFT, WIF sensor. Also the ambient air temp and cab air temp through the HEC).
Check for v-reference short by unplugging the three wire sensors and testing:
Fan speed sensor (in fan clutch connector wiring), APP, EGR valve, ICP, EBP, MAP, BARO, TPS sensors, vehicle speed sensor.
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Thread Starter
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
I think I found the issue. When I did pinpoint test H I found I have about 2.5v on pin 6 circuit 1908, According to the Workshop manual there shouldn't be any. I need to find the source of the voltage now. I'll start at the cluster since that seen to be where the noise I hear is coming from. But I will look at the wiring diagram and check each connection starting tomorrow.
Thread Starter
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
Ok, I have come to a repair point in the Workshop Pinpoint Test H13. I have a small amount of voltage, so it states to repair the circuit. Do they mean go through the harness and find the bad wire(s). I'm guessing either circuit 1908 or 1909, the twisted pair for the CAN. Where should I start?
Thread Starter
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Laughing Gas
Joined: Aug 2018
Posts: 934
Likes: 248
From: CA
Also, I have isolated the dash wire harness from the engine wire harness at connector C146 in the engine compartment. The engine side test good with 0 ohms of resistence from the male C146 to both the ABS controller and PCM.
I did find about 90 ohms of resistance from C146 back to the DLC. So I am thinking my issue is in the cab some where. I do need to get this fixed as at some point soon I will need to get the truck smogged and the state reads from the DLC.
I am at the point where I need to remove the dash and harness to try and fix this?
I did find about 90 ohms of resistance from C146 back to the DLC. So I am thinking my issue is in the cab some where. I do need to get this fixed as at some point soon I will need to get the truck smogged and the state reads from the DLC.
I am at the point where I need to remove the dash and harness to try and fix this?
Fleet Owner
Joined: Apr 2012
Posts: 27,307
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From: Spanaway
Electrical diagnosis can and usually are very time intensive.
Unplug all the modules that use the CAN Bus and then recheck.
If you no longer see the issue in the circuit. Then plug in one module
in at a time to see when the issue shows up. Take a close look at each
plug. This can be very difficult being how far back some plugs can be.
I would also look for rodent damage.
Unplug all the modules that use the CAN Bus and then recheck.
If you no longer see the issue in the circuit. Then plug in one module
in at a time to see when the issue shows up. Take a close look at each
plug. This can be very difficult being how far back some plugs can be.
I would also look for rodent damage.