Before I get a PCM, figured I’d finish up the rest of the troubleshooting to eliminate anything else, and prevent cooking a new part too.
Ok, I was following this pages troubleshooting tree. I’m not fully sure what all these values mean, just wanted to post my findings so maybe someone can explain, or see something obviously wrong within my numbers…I’m a little out of order, and a few extra suggestions were also checked at this time (some semi redundant info)
http://www.justanswer.com/dodge/7fsbv-ram-van-3500-i-ve-pcm-issues-dodge-ram-van.html
DLC
Pin 3 VT/BR: 2.48V
Pin 11 WT/BK: 2.45V
PCM disconected, batt neg disco C1 grounds check:
A-4 to battery ground: open
A-31 to ground: 0ohms
A-32 to ground: 0ohms
Backprobe Check PCM A4 to ground variations:
Key off, eng off: 0.1ohms
Key On, eng off: 4.3ohms
Key On, eng On: 7.1-7.8ohms (fluctuates)
PCM disconnected: open
Check for short to gnd (back probed)
A17 to gnd: 1592ohms
B31 to gnd: 1594ohms
PCM C1 Black 5V & sensor gnd (C1 disco)
A17: 5.16V, no short to gnd, no short to B+ 12V
A4 to A17: 567 ohms
PCM C1 Black 12V pwr & gnds(PCM disco)
A2: 12V key on, 0V key off
A22: 12.54V
A31/A32: 0ohms gnd key off, 1ohm gnd key on
Also used a test light on all 4, to opposite battery pole. All 4 lit bright = to across battery, so no noticeable voltage drops in these circuits
PCM C2 White 5V Sensor (PCM disco)
Pin 31: 5.15V, no short to gnd, no short to B+ 12V
PCM connected, Batt Connected, key off (backprobe) checking for shorts between 5V,12V, & gnd
A4 to Batt-: 0ohms
A4 to Batt+: open
A4 to A31: 0ohms
A4 to A32: 0ohms
A17 to Batt-: 1573ohms
B30 to Batt+: open(after one sec)
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The Transmission Solenoid connector does show signs of ATF staining on that harness up a few inches. I took off about a foot of electrical tape to inspect, wiped wires down. All wires look great, no damage, insulation solid and not falling apart.
Trans Short check via PCM (PCM disco, trans connected):
B31 to B8: open
B31 to B11: open
B31 to B12: 7.30Kohms
B31 to B30 7.36Kohms
Trans Short check via PCM (PCM disco, trans disco)
B31 to B8: open
B31 to B11: open
B31 to B12: open
B31 to B30 open
B30 to B8: open
B30 to B11: open
B29 to B8,11,12,30,31: open
B30-B12: 84.5ohms
B8 to gnd: open
B11 to gnd: open
B12 to gnd: 18.7ohms (also same ohms to A$ sensor gnd)
B29 to gnd: open
B30 to gnd: 80.2ohms (also same ohms to A$ sensor gnd)
B31 to gnd: open
Ran a loop with jumper cables to test wire resistances:
PCM C2 White to Trans Solenoid Assembly Connector Black (8-pin)
B29 to T4: 0.2ohms (Governor Pressure Solenoid x2)
B30 to T1: open (Trans Relay Cont to Trans Relay Control Output)
B30 to T3: 72.5ohms (Trans Relay Cont - Sensor gnd)
B31 to T2: 0.1ohms (5V power supply)
from the descriptions of the pins in the factory service manual, I thought B30 (Transmission control relay control) should be the same wire as T1 (transmission control relay output), but those 2 are open to each other. B30 instead was closest to T3(sensor ground) at 72.5ohms. This all confused me.
disconnected jumper loop:
No trans solenoid connector pins/wires shorted to each other
Trans solenoid connector assy:
Pin 2 VT/WT: 5.15V key on, not short to B+ 12V, 1831ohms to gnd?
Pin 3: 0ohms to gnd key off, 4.1ohms to gnd key on
Trans Solenoid Assy PCM disco:
Pins 1-8 are not shorted to gnd or B+ 12V
Trans Solenoid Assy PCM connected:
Pin 1: open
Pin 2:1831ohms to gnd, open to B+(after 1 sec)
Pin 3: 0ohms to gnd, not short to B+ 12V
Pin 4: 8.89Kohms to gnd, 1490ohms to B+ 12V
Pin 5: open
Pin 6: open to gnd, 6.22Kohms to B+
Pin 7: open to gnd, 6.22Kohms to B+
Pin 8: 889Kohms to gnd, 1498ohms to B+ 12V
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Sensors:
PCM Disco, ohms checks (from PCM):
A4 (sensor ground) to B31 (5 v supply - trans) = 6.67Kohms
A17 to B31 = 7.24Kohms
A17 to A4 = 567ohms
A17 to A8 (ckps) = open
A17 to A15 (IAT) = 17.15Kohms
A17 to A16 (ECT) = 17.64Kohms
A17 to A18 (cmps) = open
A17 to A23 (tps) = 1055ohms
A17 to A27 (MAP) = open
A17 to C25 (generator driver) = open
A17 to C 15(batt temp) = 18.94Kohms
A4 to B29 (GPS signal) = open
A4 to B31 (5 supply secondary) = 6.67Kohms
A4 to B1 (Trans Temp) = 1806ohms
TPS
Pin 1: 5.16V
Pin 3: 0ohms to gnd
Pin 1 to Pin 3: open after 1 sec
Cam Pos Sensor
Pin 2: 0.1 ohms to gnd
Pin 3: 5.16V
Pin 2 to pin 3: open (after one sec)
Crank Pos Sensor
Pin 2: 0.1ohms to gnd
Pin 3: 5.17V
Pin 2 to pin 3: open (after one sec)
found one pinch/chafed wire on trans harness, it went to one of the 02 sensors. cut pinch out and put butt splice in. Didn't seem to change anything.
O2 sensors PCM connected:
Pin 1: 7.22kohms to Batt+, not shorted to ground, not shorted to other wires
Pin 2: 1.6ohms to gnd, 0ohms to pin 3 (gnd), not shorted to B+ or other wires
Pin 3: 4.7ohms to gnd, 0ohms to pin 2 (gnd), not shorted to B+ or other wires
Pin 4: 7.22kohms to Batt+, not shorted to gnd or other wires
O2 sensors PCM disconnected:
Pin 1: open to B+, gnd, other wires
Pin 2: 0 ohms to gnd, open to B+ and other wires.
Pin 3: open to gnd (sensor gnd wire)
Pin 4: open to B+, gnd, other wires
Both O2 sensors wiring shot identical. Pins 1,2,3 were 0.1ohms to the other corresponding 1,2,3.
Pin 4 on both was open to each other, and appears not to be a shared line anyways.
PCM connected:
Pins 2 & 3 are 0ohms to each other and gnd
PCM disco:
Only pin 2 gets gnd, no more continuity between 2 to 3
One thing that did stand out as odd to me: Shooting some pins to ground, or shooting between pins at a sensor, it would flash random ohms for a second, then go open. I was guessing this might be shooting into the PCM, and the circuitry inside it does something for a split second. Tried with PCM unplugged, and still got 1sec of ohms, then open. Could just be cheap multimeter acting up…