Does anyone know the proper signal voltage specs for the CPS at the ECU?

the t3d

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The CPS passed the bench test with proper gap distances and resistance values, but I'm losing crank signal still and it won't start. It's kind of intermittent as well. All other ignition components have been tested, passed, and even swapped. The CPS or the wiring is the only culprit. I know what each wire does from reading, but I haven't found what the signal voltage amounts should be at the ECU. And I assume those measurements would be done while the engine is cranking, no? I plan on rewiring the whole damn CPS harness anyways, but I've tested so much shit on this car, I GOTS TO KNOW! Also, is the wiring and connector that's secured to the CPS removable? Is it possible to replace that as well, or rewire it? Anyways, thank you in advance!
 

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The CPS passed the bench test with proper gap distances and resistance values, but I'm losing crank signal still and it won't start. It's kind of intermittent as well. All other ignition components have been tested, passed, and even swapped. The CPS or the wiring is the only culprit. I know what each wire does from reading, but I haven't found what the signal voltage amounts should be at the ECU. And I assume those measurements would be done while the engine is cranking, no? I plan on rewiring the whole damn CPS harness anyways, but I've tested so much shit on this car, I GOTS TO KNOW! Also, is the wiring and connector that's secured to the CPS removable? Is it possible to replace that as well, or rewire it? Anyways, thank you in advance!

at speed anywhere from about 5v during cranking to about 30v or more at high rpm. you need am oscope to really figure that out.
 
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the t3d

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at speed anywhere from about 5v during cranking to about 30v or more at high rpm. you need am oscope to really figure that out.
Ohhhh. I didn't think it would get that high. I figured maybe a 0-12v range, but if it is starting at 5v, that at least gives me a baseline to what I should be looking for. Thank you very much. We have an o-scope at my school, so I may take mine off after I see what it's putting out on the car, and then compare what it's putting out off the car. It would just need the power supply pin connected and then the Ne pin connected to the scope right?
 

the t3d

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Driftmotion sells the connectors and proper pins sold separate.
I'm probably going to purchase that, along with that magnet mod. I also found a site called Yotaconnectors.com that sells a good amount of MK3 wiring components, including a whole new CPS harness from the ECU to the CPS. Very reasonably priced too.
 

figgie

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Ohhhh. I didn't think it would get that high. I figured maybe a 0-12v range, but if it is starting at 5v, that at least gives me a baseline to what I should be looking for. Thank you very much. We have an o-scope at my school, so I may take mine off after I see what it's putting out on the car, and then compare what it's putting out off the car. It would just need the power supply pin connected and then the Ne pin connected to the scope right?
No.

The cps is self powered. One way you will have a falling edge (that will be backwards) and the correct way you will have a rising edge. The 5v might be optimistic. Again, the best way is to put an o-scope to it and measure at cranking and then at speed (remember the CPS will be spinning half as fast as the motor so if the engine is spinning at 6000 rpm, the cps will be spinning at 3000 rpm.



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the t3d

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No.

The cps is self powered. One way you will have a falling edge (that will be backwards) and the correct way you will have a rising edge. The 5v might be optimistic. Again, the best way is to put an o-scope to it and measure at cranking and then at speed (remember the CPS will be spinning half as fast as the motor so if the engine is spinning at 6000 rpm, the cps will be spinning at 3000 rpm.



Starting on page 24...
Oh awesome, thank you. That's super helpful. Unfortunately, the oscilloscope I have access to has to remain at school, so I'd just have to remove the CPS and mimic cranking in the lab. I just won't be able to get the accurate readings from the CPS at the ECU unfortunately. I am reading the Ne pin's output then? Would I be connecting to another pin in the connector as well? Man, it's been like 10 years since I've used an o-scope. I forget if it give readings with just one lead connected. Now I want to buy one. Thank you again for the help.
 

figgie

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Oh awesome, thank you. That's super helpful. Unfortunately, the oscilloscope I have access to has to remain at school, so I'd just have to remove the CPS and mimic cranking in the lab. I just won't be able to get the accurate readings from the CPS at the ECU unfortunately. I am reading the Ne pin's output then? Would I be connecting to another pin in the connector as well? Man, it's been like 10 years since I've used an o-scope. I forget if it give readings with just one lead connected. Now I want to buy one. Thank you again for the help.
basic electricity.

If there is no complete circuit, there will be no reading.

You will need G- (ground) and NE (positive) and might as well check G1 (positive) and G2 (positive) also while you are at it. the signal should be similar as in that PDF I linked you.

with a 4 channel scope, you can get all three signal at that same time.
 

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If you're lucky maybe a local owner has an extra you could test to confirm your cps is the actual culprit.

From what I remember when I worked on the CPS wiring the sensors weren't really able to be replaced so you would have to clip and replace with fresh wire. Mine was crusty so I cracked the dried out wire covering removed it and fitted a few layers of heat shrink over it since the copper looked in decent shape still.
Used fresh wiring to extend out of the housing and connect to the plug.
Been working great ever since. Just be sure to recheck the air gaps when you reassemble.

You might want to look into these if you see any oil inside the cps housing also.
Same thing basically. It's a bit of work but turned out great.

 
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the t3d

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basic electricity.

If there is no complete circuit, there will be no reading.

You will need G- (ground) and NE (positive) and might as well check G1 (positive) and G2 (positive) also while you are at it. the signal should be similar as in that PDF I linked you.

with a 4 channel scope, you can get all three signal at that same time.
Dude, thank you very much.
 

the t3d

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If you're lucky maybe a local owner has an extra you could test to confirm your cps is the actual culprit.

From what I remember when I worked on the CPS wiring the sensors weren't really able to be replaced so you would have to clip and replace with fresh wire. Mine was crusty so I cracked the dried out wire covering removed it and fitted a few layers of heat shrink over it since the copper looked in decent shape still.
Used fresh wiring to extend out of the housing and connect to the plug.
Been working great ever since. Just be sure to recheck the air gaps when you reassemble.

You might want to look into these if you see any oil inside the cps housing also.
Same thing basically. It's a bit of work but turned out great.

Okay that is good to know. I remember doing a similar heatshrink repair in one of the CPS wires because it was breaking, but it wasn't as thorough as I'd probably have liked it to be. I definitely noticed a fair amount of green corrosion in the wires though. I am probably just going to replace the whole harness with fresh wires. The only good thing is that it's not leaking oil at least haha. Thanks for info man.