Getting up arrow and check engine light on after repairing PNP switch Topic is solved

[misha]

If you can't start the engine in "N" and reverse lights comes ON when in "R"...you need to re-adjust the pnp switch a bit more....you are pretty close.

There are marks that needs to be alligned on pnp switch but in practice it's a bit hard without a special alignment tool.

I replaced pnp switch few years ago and got pretty much the same result like you....have reverse lights in R but no start in N...only in P.
Re-aligned a switch with a helper inside the cabin and all worked as it should.

However....i didn't experienced any other problems because i didn't left garage untill i re-aligned pnp switch properly.

[rgroove54]

If you can't start the engine in "N" and reverse lights comes ON when in "R"...you need to re-adjust the pnp switch a bit more....you are pretty close.

There are marks that needs to be alligned on pnp switch but in practice it's a bit hard without a special alignment tool.

I replaced pnp switch few years ago and got pretty much the same result like you....have reverse lights in R but no start in N...only in P.
Re-aligned a switch with a helper inside the cabin and all worked as it should.

However....i didn't experienced any other problems because i didn't left garage untill i re-aligned pnp switch properly.

Hi Misha, thanks for your reply. Good to know I'm close. Please tell me if my approach to readjusting the PNP switch is correct?

1.Leave the gear selector in Park.
2. Undo and lift the shifter cable from the transmission shaft/rod it slots into.
3. Loosen the two 17mm bolts on each side of the PNP switch to get movement on the switch.
4. Align the groove on the PNP switch with the transmission shaft/rod (which is currently in the Park position). *** I'll have to fabricate my own alignment tool ***
5. Tighten the two 17mm bolts.

Many thanks for any advice.

[misha]

I just followed the write-up you allready have.
Lack of precise view from above for alignment marks will get you pretty close...but you need to figure it out where the signal for reverse lights starts and where it ends....somewhere in between is perfect.

Write-up says that transmission should be in N...but that didn't worked for me....it was pretty close but not properly aligned.

I discovered that it was easier for me when shifter was in R.

[aeg]

Just to make sure I have this right, I'm looking down into the ECU and TCU housing and I hook up my multimeter like so and test continuity on pins A3 (jn P, R,N, D, 3, L), A4 (jn P, R,N, D, 3, L), A5 (jn P, R,N, D, 3, L) and A6 (jn P, R,N, D, 3, L)?

Yes, that's right.

If you look at the chart in the lower-left corner of the wiring diagram, "A" is A3, "B" is A4, "C" is A5, "PA" is A6. Where there is an X in the chart, you want to see less than 10 ohms. If there is no X, then you want to see high resistance, your meter might display that as something like OL, the same thing you see when the probes aren't touching anything. So for example, in 3rd gear, there is an X in every column of the chart, so you would want to see less than 10 ohms on all 4 pins A3, A4, A5, A6. But in park, there is only an X in A and PA, so you would want to see less than 10 ohms on A3 and A6, high resistance on A4 and A5.

[rgroove54]

Thanks aeg, very useful information. I'll do that after the Christmas holiday.

Merry Christmas

[rgroove54]

Just to make sure I have this right, I'm looking down into the ECU and TCU housing and I hook up my multimeter like so and test continuity on pins A3 (jn P, R,N, D, 3, L), A4 (jn P, R,N, D, 3, L), A5 (jn P, R,N, D, 3, L) and A6 (jn P, R,N, D, 3, L)?

Yes, that's right.

If you look at the chart in the lower-left corner of the wiring diagram, "A" is A3, "B" is A4, "C" is A5, "PA" is A6. Where there is an X in the chart, you want to see less than 10 ohms. If there is no X, then you want to see high resistance, your meter might display that as something like OL, the same thing you see when the probes aren't touching anything. So for example, in 3rd gear, there is an X in every column of the chart, so you would want to see less than 10 ohms on all 4 pins A3, A4, A5, A6. But in park, there is only an X in A and PA, so you would want to see less than 10 ohms on A3 and A6, high resistance on A4 and A5.

Hi aeg, I carried out the test you suggested on the TCU connectors pins (using the continuity setting on my multimeter) and I didn't get any tone from each of the pins. Should the ignition be on ie in position I or II, but the engine not running? My multimeter display said 'I' all the time. I tested the probes beforehand and they are fine. Does this mean the wiring in the existing PNP switch is broke and I need a new PNP switch? I replaced my TCU with another TCU that has the exact same TCU software version, but I'm still having an issue. I do feel the transmission engaging when I select the gears each time. My ATF fluid level is within range.

This is a summary of where I am right now:

1. The car now starts in P and N, after I readjusted the PNP switch. I could only start in P before.
2. Reverse lights are coming each time in the ignition II position.
3. I'm still get the up arrow and check engine light, even after clearing the DTC codes several times.
These are the codes I still get:
AT-313 gear position sensor faulty signal
EFI-666 DTC in a transmission CM
4. The E and W lights by the gear selector are flash back and forth.

Any advice on what to do next will be much appreciated. I feel as though I'm out of my depth now. Many thanks.

[misha]

Re-reading your posts again...i did not quite understood was the problem present before pnp switch rebuilt or it appeared after the rebuilt?

[aeg]

Just to make sure I have this right, I'm looking down into the ECU and TCU housing and I hook up my multimeter like so and test continuity on pins A3 (jn P, R,N, D, 3, L), A4 (jn P, R,N, D, 3, L), A5 (jn P, R,N, D, 3, L) and A6 (jn P, R,N, D, 3, L)?

Yes, that's right.

If you look at the chart in the lower-left corner of the wiring diagram, "A" is A3, "B" is A4, "C" is A5, "PA" is A6. Where there is an X in the chart, you want to see less than 10 ohms. If there is no X, then you want to see high resistance, your meter might display that as something like OL, the same thing you see when the probes aren't touching anything. So for example, in 3rd gear, there is an X in every column of the chart, so you would want to see less than 10 ohms on all 4 pins A3, A4, A5, A6. But in park, there is only an X in A and PA, so you would want to see less than 10 ohms on A3 and A6, high resistance on A4 and A5.

Hi aeg, I carried out the test you suggested on the TCU connectors pins (using the continuity setting on my multimeter) and I didn't get any tone from each of the pins. Should the ignition be on ie in position I or II, but the engine not running? My multimeter display said 'I' all the time. I tested the probes beforehand and they are fine. Does this mean the wiring in the existing PNP switch is broke and I need a new PNP switch? I replaced my TCU with another TCU that has the exact same TCU software version, but I'm still having an issue. I do feel the transmission engaging when I select the gears each time. My ATF fluid level is within range.

This is a summary of where I am right now:

1. The car now starts in P and N, after I readjusted the PNP switch. I could only start in P before.
2. Reverse lights are coming each time in the ignition II position.
3. I'm still get the up arrow and check engine light, even after clearing the DTC codes several times.
These are the codes I still get:
AT-313 gear position sensor faulty signal
EFI-666 DTC in a transmission CM
4. The E and W lights by the gear selector are flash back and forth.

Any advice on what to do next will be much appreciated. I feel as though I'm out of my depth now. Many thanks.

Key position doesn't matter. For this test, electricity flows from the meter, through the wiring, to the switch, and back to the meter, without involving any other part of the car.

It's surprising that the gear position portion of the switch seems to be completely open-circuit, but the PNP portion is working.

I think the first thing to do is confirm the meter is working correctly. If you touch the probes together on the continuity setting, the reading should change from I to about 1 or 2.

Another quick check would be is A3 to A6 at the TCM connector, with the lever in park. If A3 to A6 is less than 10 ohms, but A3 to A20 is high resistance, then the switch contacts are OK but the ground is open.

Another sanity test is A20 to A29 at the TCM connector, should be less than 5 ohms.

You could also check the switch at the transmission connector, with the harness that goes to the rest of the car disconnected. With the lever in park, pin 1 should be less than 10 ohms to the metal casing of the switch (but if the switch is faulty, it will be high resistance). As a sanity check, since we know the PNP portion works, pin 6 to pin 7 should be less than 10 ohms. If not, there is something wrong with the measuring technique.

Another thing worth checking is resistance from the metal casing of the switch to the metal casing of the transmission. If this is open circuit, then the TCM won't see any of the gear selector inputs.

trans_connector_2.gif (60.88 KiB) Viewed 309 times

[rgroove54]

Yes, that's right.

If you look at the chart in the lower-left corner of the wiring diagram, "A" is A3, "B" is A4, "C" is A5, "PA" is A6. Where there is an X in the chart, you want to see less than 10 ohms. If there is no X, then you want to see high resistance, your meter might display that as something like OL, the same thing you see when the probes aren't touching anything. So for example, in 3rd gear, there is an X in every column of the chart, so you would want to see less than 10 ohms on all 4 pins A3, A4, A5, A6. But in park, there is only an X in A and PA, so you would want to see less than 10 ohms on A3 and A6, high resistance on A4 and A5.

Hi aeg, I carried out the test you suggested on the TCU connectors pins (using the continuity setting on my multimeter) and I didn't get any tone from each of the pins. Should the ignition be on ie in position I or II, but the engine not running? My multimeter display said 'I' all the time. I tested the probes beforehand and they are fine. Does this mean the wiring in the existing PNP switch is broke and I need a new PNP switch? I replaced my TCU with another TCU that has the exact same TCU software version, but I'm still having an issue. I do feel the transmission engaging when I select the gears each time. My ATF fluid level is within range.

This is a summary of where I am right now:

1. The car now starts in P and N, after I readjusted the PNP switch. I could only start in P before.
2. Reverse lights are coming each time in the ignition II position.
3. I'm still get the up arrow and check engine light, even after clearing the DTC codes several times.
These are the codes I still get:
AT-313 gear position sensor faulty signal
EFI-666 DTC in a transmission CM
4. The E and W lights by the gear selector are flash back and forth.

Any advice on what to do next will be much appreciated. I feel as though I'm out of my depth now. Many thanks.

Key position doesn't matter. For this test, electricity flows from the meter, through the wiring, to the switch, and back to the meter, without involving any other part of the car.

It's surprising that the gear position portion of the switch seems to be completely open-circuit, but the PNP portion is working.

I think the first thing to do is confirm the meter is working correctly. If you touch the probes together on the continuity setting, the reading should change from I to about 1 or 2.

Another quick check would be is A3 to A6 at the TCM connector, with the lever in park. If A3 to A6 is less than 10 ohms, but A3 to A20 is high resistance, then the switch contacts are OK but the ground is open.

Another sanity test is A20 to A29 at the TCM connector, should be less than 5 ohms.

You could also check the switch at the transmission connector, with the harness that goes to the rest of the car disconnected. With the lever in park, pin 1 should be less than 10 ohms to the metal casing of the switch (but if the switch is faulty, it will be high resistance). As a sanity check, since we know the PNP portion works, pin 6 to pin 7 should be less than 10 ohms. If not, there is something wrong with the measuring technique.

Another thing worth checking is resistance from the metal casing of the switch to the metal casing of the transmission. If this is open circuit, then the TCM won't see any of the gear selector inputs.

trans_connector_2.gif

Thanks for your reply aeg. Sounds like you've had this issue yourself. I was testing at the wrong end of the TCU connection, so I retested and these are my readings. So, I'm not getting continuity on quite a few pins where the X is, in relation to the gear position and pin.

TCU continuity test.jpg (20.21 KiB) Viewed 295 times

At the TCU connection where the TCU module sits in:
Continuity between A3 and A6, I get nothing, just the '1' or 'I' displayed. ***I hope I did this right like so.

A3 to A6.jpg (105.7 KiB) Viewed 288 times

Continuity between A3 and A20, I get nothing, just the '1' or 'I' displayed. ***I hope I did this right like so.

A3 to A20.jpg (105.13 KiB) Viewed 288 times

Continuity between A20 and A29, I get a reading of 001 (and the beep). ***I hope I did this right like so.

A20 to A29.jpg (105.6 KiB) Viewed 288 times

At the wiring harness connection:
Continuity between pin 1 and the metal casing of the PNP switch, I get nothing, just the '1' or 'I' displayed. ***I hope I did this right.
Continuity between pin 6 to pin 7, I get a reading of 001 (and the beep) and I connected my multimeter like this:

Screenshot 2025-12-29 160550.jpg (44.76 KiB) Viewed 287 times

When you mean Another thing worth checking is resistance from the metal casing of the switch to the metal casing of the transmission. If this is open circuit, then the TCM won't see any of the gear selector inputs. do you mean place one probe on the PNP switch case and the other probe on any metal part of the transmission, as indicated by the blue line?

Screenshot 2025-12-23 151832.jpg (93.46 KiB) Viewed 295 times

I also checked the connections between the TCU connector pins and the plug with the pink gasket (which plugs into the connector next to the PNP switch. I connected my multimeter like so:

These are my readings (TCU pin number on the left, pink gasket pin number on the right). I get a continuity beep each time.

3 and 1 = 002 ohms
4 and 2 = 002 ohms
5 and 3 = 002 ohms
6 and 4 = 002 ohms

I really appreciate your time with this.

[aeg]

OK! So the switch contacts for C, PA, 50S and BL are good, but A and B are open circuit. Also, the wiring between the ECU box and the transmission is OK. You need to replace the switch or redo the repair.

No need to measure across the blue line. Now that we know A20 to A5/A6 are OK, we know the ground connection of the switch is OK.