Real Quick CPS Question (Renix) - JeepForum.com
 
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post #1 of 12 Old 12-17-2015, 12:16 AM Thread Starter
YJjeeper1
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Real Quick CPS Question (Renix)

Hi guys I have a real quick question, I am chasing down a no spark condition and just need a verification on what voltage the Crankshaft Position sensor should be receiving from the ECU and what it should put out. Also, is there voltage present with key in on Position with vehicle off? Already did the ohms test as well as the A/C voltage, suspecting a wiring harness issue so need a reference. This is on a 2.5 Renix System with 2 wire CPS, Thanks!

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post #2 of 12 Old 12-17-2015, 01:56 PM Thread Starter
YJjeeper1
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Turns out that I'm getting 3.16v on both sides of the CPS wire, is this right?
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post #3 of 12 Old 12-17-2015, 04:52 PM
Drednot
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The wt/bk wire is sensor ground through ECU pin 27.
The red wire is the sensor input.
If its just a two wire, I think its just a pulse generator. ohms between A and B should be 200 +/- 75 when engine is hot. If not, replace sensor.

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35@3.07
12 Cherokee 4x4,3.7L,42RLE/MP1522, D30M/8.25@3.73
Emission test=YES
"Non Vi Sed, Arte"
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post #4 of 12 Old 12-17-2015, 05:10 PM Thread Starter
YJjeeper1
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Well I tested it the unit cold and it sits at about 205 cold, other one is at 212(I keep a spare). However since I can't get it to start due to no spark, it's impossible to get it to test hot. So the voltage does not matter like it does on the HO 3 wire CPS?
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post #5 of 12 Old 12-17-2015, 09:59 PM
Drednot
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How are you checking for voltage? Black to ground and red to each wire? And reading three volts off either?

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35@3.07
12 Cherokee 4x4,3.7L,42RLE/MP1522, D30M/8.25@3.73
Emission test=YES
"Non Vi Sed, Arte"
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post #6 of 12 Old 12-20-2015, 02:25 AM Thread Starter
YJjeeper1
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Quote:
Originally Posted by Drednot View Post
How are you checking for voltage? Black to ground and red to each wire? And reading three volts off either?
Yes sir, black to ground and negative terminal, positive coming off both the input and output wires going into the CPS. Same voltage on both. At wits end honestly, going to just take it in to a Jeep specialist shop.
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post #7 of 12 Old 12-20-2015, 01:41 PM
Drednot
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So, the disconnected CPS is giving you a voltage reading? Or is it the harness end that you are checking?

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35@3.07
12 Cherokee 4x4,3.7L,42RLE/MP1522, D30M/8.25@3.73
Emission test=YES
"Non Vi Sed, Arte"
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post #8 of 12 Old 12-20-2015, 11:33 PM Thread Starter
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The Harness end is giving me that reading, even with the CPS disconnected.
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post #9 of 12 Old 12-21-2015, 08:26 PM Thread Starter
YJjeeper1
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Could a bad distributor be the cause of a no spark, even though there's no Camshaft Sensor on these 2.5 Renix models? At this point, the Ignition Control Module is new as well as a new Coil. Plus tested the CPS and my spare CPS and both test good ohms, 212 and 207 respectively, which is good according to what I've read.
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post #10 of 12 Old 12-23-2015, 12:57 PM
Que89YJ
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3 volts is low. You should see 5vdc. Did you read the voltage with the sensor hooked up or disconnected?
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post #11 of 12 Old 12-23-2015, 05:31 PM
Drednot
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Quote:
Originally Posted by Que89YJ View Post
3 volts is low. You should see 5vdc. Did you read the voltage with the sensor hooked up or disconnected?
He has a two wire CPS.
In reading the diagnostic procedures, it sounds like a pulse generator style and shouldn't receive ant volts from the CPU

I don't have an 89 so I cant check my own. Can you check your connector and see if yours shows three volts at the harness? on and off?

A lot of tests in the diagnostic manual ask if the volts go "over 3 volts" "yes" or "no"

makes me wonder if there is a low voltage hanging around all the time???

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35@3.07
12 Cherokee 4x4,3.7L,42RLE/MP1522, D30M/8.25@3.73
Emission test=YES
"Non Vi Sed, Arte"
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post #12 of 12 Old 12-23-2015, 10:19 PM
Que89YJ
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Quote:
Originally Posted by Drednot View Post

He has a two wire CPS.
In reading the diagnostic procedures, it sounds like a pulse generator style and shouldn't receive ant volts from the CPU

I don't have an 89 so I cant check my own. Can you check your connector and see if yours shows three volts at the harness? on and off?

A lot of tests in the diagnostic manual ask if the volts go "over 3 volts" "yes" or "no"

makes me wonder if there is a low voltage hanging around all the time???
It should be a hull effect. I will check it tomorrow.

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