Fuhnortoner

2000 Camaro LS1 swap into an RX7 with a custom harness. Frost mail order SD tune. Mild cam, Short tubes.

Throwing codes P1635 and P1639. (also P0103 due to SD tune)

Engine runs great. Only problem is the tranny shifts hard like the pressure is high, I belive the codes are probably the root cause.

P1635 is 5v circuit #1, and P1639 is 5v circuit #2.

For the 5v circuit #1, the only sensors I'm using that are relevant are TPS and MAP, which both have been replaced with oem.

For 5v circuit #2, I'm not using any sensors on that circuit. (AC pressure and FTPS)

Have 5v at TPS and MAP.

Sensor ground resistance from sensor plugs to body ground is 0 with key off.

Heres a weird thing. With the key on, the sensor ground resistance from sensors to body jumps to 3ohms. not sure if this is normal. All of the sensors are reading fine on the OBD scanner.

I've heard this can be a short within the PCM. Just trying to see if ive overlooked anything before I buy another PCM

Appreciate any insight on this.

Freeze frame report generated by Torque for Android
================================================== =======

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present

Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 4.706 %
Engine Coolant Temperature = 89.6 °F
Fuel Trim Bank 1 Short Term = -0.781 %
Fuel Trim Bank 1 Long Term = 21.094 %
Fuel Trim Bank 2 Short Term = -0.781 %
Fuel Trim Bank 2 Long Term = 9.375 %
Intake Manifold Pressure = 8.992 psi
Engine RPM = 1,163.25 rpm
Speed (OBD) = 0 mph
Mass Air Flow Rate = 12 g/s
Throttle Position(Manifold) = 0.392 %


End of report.

Fuhnortoner

Bump. Bueler? Bueler?

Fuhnortoner

Im just going to start logging everything I do in this thread for the next guy. I cant find any relevant information on this thread with a solution so I'll handle it.

I've just read that 5v circuit 1 and 5v circuit 2 are connected together inside the PCM. Apparently when both codes go, it indicates the circuit is shorted to a voltage. Im having a tough time figuring this one out because I have 5.3v to the TPS, 5.3v to the MAP sensor, and I have no other sensors connected to either circuit. I would think a 12v short would show 12v on all of the reference wires.

Next step is to probe at the back of the harness at the PCM on all of the 5v references and make sure i dont have 12v on any of them.

Im also going to pull out the harness plug from the PCM and check continuity between all 12v pins and 5v pins to make sure theres not a wiring short.

Fuhnortoner

All of the 5v Ref wires are receiving 5.3v with the engine running. Even the wires I'm not using (I pinned them at the PCM).

So, with the PCM UNPLUGGED and the KEY ON I was checking the harness at the plug for shorts. Right off the bat I noticed I was getting .7 volts on my 5v Ref wires, when I believe I should be getting zero. Right? The wires are only connected to the TPS and the MAP sensor, which are completely disconnected from the PCM, so I start to pull fuses. I have Bank 1 Injectors and Coils on one 15a 12v circuit, and Bank 2 Injectors and Coils on another 15a 12v circuit. When I unplug these fuses the voltage goes to zero.

I was running out of daylight so I started checking continuity on each wire with ground, harness unplugged with the key off. I found some interesting results.

GROUND TO:

BLUE 17 - 1.6 OHMS - TRANS PRESSURE SWITCH B
BLUE 26 - 0 OHMS - HO2 LOW SIGNAL BANK 2 SENSOR 1
BLUE 29 - 0 OHMS - HO2 LOW SIGNAL BANK 1 SENSOR 1
BLUE 33 - 8.9 OHMS - TCC BRAKE SWITCH (with key on I get 12v, its connected to brake light switch

RED 33 - 0 OHMS - HIGH SPEED FAN RELAY

I also check continuity from 12v to all pins harness unplugged with the key off. I only got 12v on the 2 battery 12v wires.

I need to do some research but I'm pretty sure there's a problem with BLUE 17 being grounded. I think the HO2s are probably fine, and the Fan and TCC switch are both on NC Realys (Pin 87a on the relay) which is causing the continuity. And like I stated earlier, TCC is showing 12v when I step on the brake.

I hate electrical.

Fuhnortoner

Can anyone tell me if I should have any voltage on the 5v Ref wire with the ECU unplugged?

EFIHARNESS

On a lot of harnesses there is only one 5v+, and one signal ground brought out of the ecu. If the ecu is disconnected and system is powered up you will get bogus readings thru sensors. Pm me .Steve

Fuhnortoner

I made this custom PCM harness. I brought a dedicated 5v out for each sensor im using from the PCM.

Tell me this. with the PCM disconnected, and the ignition on, Im getting .7 volts on the 5v ref wire. When I remove the fuse for INJ/COIL BANK 1 it drops to .4v, and when I remove the fuse for INJ/COIL BANK 2 it drops to 0v. Does that sound normal?

Fuhnortoner

Dont see any corrosion or burn marks

EFIHARNESS

Yes, it is normal because the coils have drivers in them that share a common signal ground with the 5v sensors. Steve

Fuhnortoner

Ok I'm going to be the first person on this forum to ever follow up with this problem. Unfortunately, unless you reworked your own harness like I did (swap), or if you dont have an automatic trans, it's not going to be your problem.

I mispinned C1/BLUE 53 (trans temp low ref) into C2/RED 53 (traction control). I put it back to C153, cleared the codes, and never saw them again. My car shifts way better, 1-2 shift error is at .3 seconds from 6 seconds.

Also thanks to Steve for being the only person to attempt to help me with this problem. I always appreciate it when anyone takes the time out of their day to help me.