Resolved 2G Diagnosing no rpm signal

[v8s_are_slow]

I'll see what I can figure out on my short lunch break today. Just not sure which wire at the coils to check. And the capacitor is in there somewhere. All underneath my intake manifold. Blah!!!

 

[v8s_are_slow]

Okay, I'm, double checking some of my work. Pin 58 at the ecu to Pin 24 of C-05 at the cluster was good. I think the ground from the cluster is good. But if I'm checking for continuity from Pin 4 at the ptu to the cluster, can someone PLEASE point out the correct pin so that I'm SURE I'm testing the right one? I'm not sure that I am testing it correcting and I'm wondering if I found the issue. Thanks!!!

 

[19Eclipse90]

PTU:

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[info removed]

But... you verified this already in post #16, I thought?

 

[v8s_are_slow]

I'm sorry, I meant that I needed to know which one was Pin 4 on C-04. I read that like multiple times to make sure it made sense too, and it still didn't. Sorry about that.

If I'm doing this right, this is what I'm getting.

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[v8s_are_slow]

Thanks. Trying that again and here's what I get.

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[v8s_are_slow]

Not trying to sound like an idiot but I guess this page is for people who don't know what they're doing like myself when it comes to electrical. However I don't know how to look at the diagram very well to determine what's what. I'm not really sure what else to be checking for.

P.S. I'll check the capacitor and see if I can figure out wires from the ptu plug to the coil. But that will about max out my abilities without someone literally holding my hand. Wish me luck.

 

[steve]

Please note that the numbers on that ^ gauge cluster don't match the numbers in the wiring diagrams.

These connectors have pin positions in the middle:
So C-06 connector runs from 1 to 8 on one side and 10 to 17 on the other with 9 in the middle.
C-05 connector starts at pin 21 to 28 and 30 to 37 with 29 in the middle.
C-04 connector starts at pin 41 to 48 and 50 to 57 with 49 in the middle.
None of the middle pins are used but they take up spot.

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I'll double check what goes where after dinner.

 

[19Eclipse90]

Yeah, that's my bad. It takes more than a couple minutes to be thorough with these things and I cut some corners. My guidance with the gauge cluster pictures was incorrect and I'll be removing those pictures.

Let's see if this is any better:

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These will refer to the next picture. I'm not positive what orientation C-06 is in so I can't exactly draw arrows to it. But I think you'll get the idea.

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[v8s_are_slow]

So I changed the capacitor and tried a third ptu. No change. Only thing I haven't checked yet is the continuity between the ptu plug and the coils. But if that was bad, I would think the car wouldn't be running on all 4 cylinders...and it is.

If I need to check continuity for the capacitor, where would I check on the other side? Anything else that it could be??? I'm still wondering what role the ecu plays in this for pin 58 to be going to the ecu and the other side going to pin 4 at the ptu plug if ecmlink still reads the rpm's?

 

[steve]

I'm still wondering what role the ecu plays in this for pin 58 to be going to the ecu and the other side going to pin 4 at the ptu plug if ecmlink still reads the rpm's?

The ECU doesn't use the signal from the PTU for RPM, it has the Crank and Cam Angle signals for that. It uses the PTU signal for diagnostic input, like is the coil firing when it tells it to.

Maybe you missed this early on. The ECU doesn't use the signal on pin 58 for RPM.

 

[v8s_are_slow]

No, I saw it. Just wondering why rpm use would be at that pin? Didn't know if the ptu sent the signal to the ecu, then from there to the gauge. Apparently not. I don't understand the purpose of the wire going from pin 4 of the ptu to the pin at the ecu, if the ecu isn't going to use it. Just trying to understand the workings of it.

If that's not a possible culprit, I don't know what I'm missing.

 

[19Eclipse90]

Let's backtrack a little bit.

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The tachometer grounds through C-04 pin 44.
The tachometer gets its power through C-06 pin 10.
The tachometer gets its signal through C-05 pin 24.

The ground is easy to check, continuity from C-04 pin 44 to any ground.
The power should be okay because the rest of the gauges work and they use the same source power. Unless some trace is broken within the cluster specifically for the tachometer. Considering you've tried a different cluster, this can very likely be ruled out.
So back to the signal, which is sourced from the ignition power transistor, white wire. This brings us back to the other diagram we've looked at:

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The tachometer "circuit" (TACHO) in the PTU is providing the tach signal. The ECU, TCU (if auto), and gauge cluster receive the signal. Based on the pinouts from all over the internet, pin 58 of the ECU only looks to see that ignition is happening (labeled as Engine Ignition Signal). The tachometer "circuit" (TACHO) in the PTU is powered through PTU pin 6. PTU pin 6 should have continuity with coil pack pin 3 and the noise condensor connector, all should be black w/ white wires. I point these out because they should all be right near each other and much easier to check than the rest of the upstream circuit.

Having coil on plug setup may affect that original wiring, so it may be necessary to go further upstream. Ultimately, the source is the pin 2 of the ignition switch.

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Again, my apologies for the misguided advice earlier on. If you can cross some of these off again we can surely get to the bottom of your issue.

 

[v8s_are_slow]

No need to apologize. I'm grateful for any help I can get because I'm stuck without it otherwise.

But here's my readings on pin 6 at the ptu and both of the black wires here at the coil connector.

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[19Eclipse90]

And that's your C.O.P. plug? Do you know what each of those wires is for? Sorry, I'm not familiar enough with these to know.

Check the noise condensor connector by chance?

 

[v8s_are_slow]

And that's your C.O.P. plug? Do you know what each of those wires is for? Sorry, I'm not familiar enough with these to know.

Check the noise condensor connector by chance?

Yes sir, that's the cop plug from the ignition box. Not familiar with what wire is for what though.

I can stick a probe in the condenor. But where do I stick the other probe? This is where I'm completely stuck now.

 

[19Eclipse90]

PTU pin 6. Refer to post #28, if needed.

Here's where this is only half helpful. Since I don't know what wires do what on the C.O.P., even if PTU pin 6 has continuity with the noise condensor plug, it would tell you that run of wire between the two is good but not necessarily that that run is connected to the rest of the system.
With a stock coil pack / plug, it would be pretty straightforward.

 

[v8s_are_slow]

So just an update but I have an M&W ignition box. Didn't really think this was of importance. But someone told me I needed to disconnect the white wire at pin 4 of the ptu to pin 58, and connect the blue wire/pin 4 from the ignition box for the tach to pin 58 at the ecu instead. I'm going to try that on my lunch break here shortly. I did test for ground. I have power. So it's just a signal issue. I'm testing every free second I have....which isn't much unfortunately. But updating as I go.

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[v8s_are_slow]

Let's backtrack a little bit.

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The tachometer grounds through C-04 pin 44.
The tachometer gets its power through C-06 pin 10.
The tachometer gets its signal through C-05 pin 24.

The ground is easy to check, continuity from C-04 pin 44 to any ground.
The power should be okay because the rest of the gauges work and they use the same source power. Unless some trace is broken within the cluster specifically for the tachometer. Considering you've tried a different cluster, this can very likely be ruled out.
So back to the signal, which is sourced from the ignition power transistor, white wire. This brings us back to the other diagram we've looked at:

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The tachometer "circuit" (TACHO) in the PTU is providing the tach signal. The ECU, TCU (if auto), and gauge cluster receive the signal. Based on the pinouts from all over the internet, pin 58 of the ECU only looks to see that ignition is happening (labeled as Engine Ignition Signal). The tachometer "circuit" (TACHO) in the PTU is powered through PTU pin 6. PTU pin 6 should have continuity with coil pack pin 3 and the noise condensor connector, all should be black w/ white wires. I point these out because they should all be right near each other and much easier to check than the rest of the upstream circuit.

Having coil on plug setup may affect that original wiring, so it may be necessary to go further upstream. Ultimately, the source is the pin 2 of the ignition switch.

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Again, my apologies for the misguided advice earlier on. If you can cross some of these off again we can surely get to the bottom of your issue.

So I'm striking out at every turn thus far and while I appreciate the diagrams, I totally can not figure them out. So let's pretend for a moment that I'm on stock coils, am I thinking of this correctly with my crude diagram? I know I have power at the cluster. I have ground at the cluster. But I guess I'm not getting signal obviously. Just need to make sure I have a clear understanding, but no idea about this pin 2 at the ignition.

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[19Eclipse90]

I hope this doesn't cause confusion. So pin 2 of the ignition switch is the "power" to the TACHO interface inside of the PTU (through pin 6). It also runs to the noise condensor and coil pack pin 3. Since you aren't getting a tachometer signal out through pin 4 and you've tried a different PTU all together, the wiring from ignition switch pin 2 to tachometer pin 6 is suspect. If you had stock coils and the car was operational, the easy check would be to see if continuity between PTU pin 6 and coil pack pin 3 existed. Because the car is operational, you know that Ignition Switch pin 2 to coil pack pin 3 must be good, else the car would not start / run. Therefore, if the run between PTU pin 6 and coil pack pin 3 was good, you could assume that Ignition Switch pin 2 to PTU pin 6 was also good.

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[v8s_are_slow]

Okay, so maybe I was testing the wrong pins at the cluster at first for continuity. Because I could've sworn I had continuity everywhere I was testing. But after reading through everyone's replies and some help on Facebook, I understood how everything worked and pin numbers, etc. Except for the wiring diagrams. I don't know what the heck I'm looking at there.

Anyway, apparently I didn't have continuity between the gauge cluster and pin 58 at the ecu. So with the help of a guy named Chris Vasquez on Facebook, I managed to track down where the wire went from the cluster behind the radio area at C-22. I didn't know it came out there so that was a huge relief. I tested for continuity there at that plug to the cluster and that was good. I didn't wanna have to but I just cut the wire at the plug behind the radio and ran a wire from that to pin 58 at the ecu to bypass the break.

I dunno if this helps anyone else but feel that this post will be about the most informative on the forum for most people who have this issue due to all the pins, diagrams, etc. I sure appreciate it and I definitely wouldn't have been able to fix this without everyone here and on Facebook. This was a real kick in the butt to resolve for me and I'm definitely grateful. Thanks y'all!

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[19Eclipse90]

Glad to hear you got it fixed! And I really appreciate that you followed up to let us know you got it.

 

[v8s_are_slow]

Had a bunch of people on Facebook that are having the same issue as me, request a video of it to add to my channel. So with the help of this thread and folks on Facebook who helped me out with this issue, I did just that yesterday. Figured I'd also add it here so that other people searching the forums have something to fall back on. I didn't cover EVERY test possible, but the main ones I did here.

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