Need help with 5V Vref circuit diagnostics
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7th Gear
Joined: Sep 2025
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Need help with 5V Vref circuit diagnostics
Looking for some electrical diagnostics help…im getting some codes (B1352, P0472, P0198, P0113, P0340, P1210) for all the main engine harness sensors. It looks like all the sensors share the 5v supply and return line from the 42 pin connector. (Pins 21 and 19).
In KOEO They all have 5.04 volts on the supply side but varying voltages on the return side (icp reads 4v on return, the rest are around 2 or .2) and pin 19 on the 42 pin connector on the pcm side when plugged in key on reads 70mV. i cant find any shorts or anything and unplugging sensors one by one doesnt change the output on pin 19 on the pcm side nor do the other sensors start reading correctly.
I havent looked at the DTR OSS or TSS sensors on the same line because i am not sure where they are.
Any suggestions for tests i can do with a DVMM or test light or other diagnostics help? I would really appreciate it. I also have FORscan and can run tests as requested.
2002 4x4 auto f250. It starts and runs fine though charging batteries read around 12.5 when running but alternator output wire reads 13+. IC, GPR, and CPS are all new from DieselOrings.
Truck runs and drives and feels plenty powerful but shifts horribly and all the sensors that are throwing codes are reading arbitrary inaccurate numbers that do not change with rpm or runtime. I have looked through all the common chafing spots and found nothing.
2002 F250 7.3 4x4 Lariat
In KOEO They all have 5.04 volts on the supply side but varying voltages on the return side (icp reads 4v on return, the rest are around 2 or .2) and pin 19 on the 42 pin connector on the pcm side when plugged in key on reads 70mV. i cant find any shorts or anything and unplugging sensors one by one doesnt change the output on pin 19 on the pcm side nor do the other sensors start reading correctly.
I havent looked at the DTR OSS or TSS sensors on the same line because i am not sure where they are.
Any suggestions for tests i can do with a DVMM or test light or other diagnostics help? I would really appreciate it. I also have FORscan and can run tests as requested.
2002 4x4 auto f250. It starts and runs fine though charging batteries read around 12.5 when running but alternator output wire reads 13+. IC, GPR, and CPS are all new from DieselOrings.
Truck runs and drives and feels plenty powerful but shifts horribly and all the sensors that are throwing codes are reading arbitrary inaccurate numbers that do not change with rpm or runtime. I have looked through all the common chafing spots and found nothing.
2002 F250 7.3 4x4 Lariat
Last edited by Krsenor; Sep 30, 2025 at 07:23 PM.
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
Okay, that's identified as inline connector C110 in the Ford EVTM which is what I have on hand. Makes sense now!
Check the integrity of the connection between SIGNAL RETURN and chassis ground. IIRC, they're connected together inside the PCM. There should be a PCM chassis ground connection (G100 in the schematics) on the firewall right next to where the PCM is mounted and another (G101) on th etop of the shock tower. Do check those for poor connections due to loose screw, paint, corrosion, etc.
Check the integrity of the connection between SIGNAL RETURN and chassis ground. IIRC, they're connected together inside the PCM. There should be a PCM chassis ground connection (G100 in the schematics) on the firewall right next to where the PCM is mounted and another (G101) on th etop of the shock tower. Do check those for poor connections due to loose screw, paint, corrosion, etc.
Thread Starter
|
7th Gear
Joined: Sep 2025
Posts: 7
Likes: 0
Okay, that's identified as inline connector C110 in the Ford EVTM which is what I have on hand. Makes sense now!
Check the integrity of the connection between SIGNAL RETURN and chassis ground. IIRC, they're connected together inside the PCM. There should be a PCM chassis ground connection (G100 in the schematics) on the firewall right next to where the PCM is mounted and another (G101) on th etop of the shock tower. Do check those for poor connections due to loose screw, paint, corrosion, etc.
Check the integrity of the connection between SIGNAL RETURN and chassis ground. IIRC, they're connected together inside the PCM. There should be a PCM chassis ground connection (G100 in the schematics) on the firewall right next to where the PCM is mounted and another (G101) on th etop of the shock tower. Do check those for poor connections due to loose screw, paint, corrosion, etc.
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