Renix Disaster
#17
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Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
I replaced the ignition switch but not the key lock. My theory behind this is that the switch was making bad contact when I was putting in the start position. Every once in a while when I turned the key off quickly the engine would "kick" just once. I also hotwired the switch and that did not work but, I have started to second guess everything I do so I changed the $15 switch.
#19
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Junior Member
Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
I have also cleaned all of the connectors. I am kinda pressed for Jeep time so I haven't got to the sensor ground connections although I don't see that as a determining factor of the no spark issue. I have to lean back towards the computer, again. It has the inputs required for spark (at least the ones I know about) and it doesn't have any output.
these are the inputs I believe to be required
CPS .35 VAC or higher. I have .5 at the computer
12VDC battery voltage
12VDC ACC Voltage
Is there a signal that would be required that I am missing? As far as I can tell there are no other signals that would keep the computer from creating the spark signal.
#20
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
CJ, Just to be doubly sure...that's .5 ACV which you can also measure at the the TWO wires from your CPS, correct?
Also I just learned, two screws and two minutes and you can check that that new coil has about one ohm through the primary.
Also I just learned, two screws and two minutes and you can check that that new coil has about one ohm through the primary.
#21
Thread Starter
Junior Member
Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
Thanks for the ideas. please keep them coming!
FYI, I just thought that I haven't checked the Park/Neutral safety switch. The next opportunity I get I will check the outputs of those pins and see if they are good. I am not sure exactly how this switch effects the spark but it has to be worth a try. If anyone has any information on this switch let me know.
Currently, I am at the Fire Department for an overnight shift (volunteer firefighter) so I wont be able to look at it until tomorrow.
Last edited by Cjjcalhoun; 07-02-2017 at 04:15 PM.
#23
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Junior Member
Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
So, let me start by saying that information on this vehicle is difficult to find and almost impossible to verify.
The information that I have found is that a positive D.C. Voltage is provided by the ECM and common amongst all of the injectors (one output voltage for all injectors). The injector drivers provide a ground that is individual to each injector (one wire for each). So when I say I am missing the injector signal I am missing the D.C. voltage. I assume that this is a 5v signal but I don't know that for sure.
The information that I have found is that a positive D.C. Voltage is provided by the ECM and common amongst all of the injectors (one output voltage for all injectors). The injector drivers provide a ground that is individual to each injector (one wire for each). So when I say I am missing the injector signal I am missing the D.C. voltage. I assume that this is a 5v signal but I don't know that for sure.
#24
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,565
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
So, let me start by saying that information on this vehicle is difficult to find and almost impossible to verify.
The information that I have found is that a positive D.C. Voltage is provided by the ECM and common amongst all of the injectors (one output voltage for all injectors). The injector drivers provide a ground that is individual to each injector (one wire for each). So when I say I am missing the injector signal I am missing the D.C. voltage. I assume that this is a 5v signal but I don't know that for sure.
The information that I have found is that a positive D.C. Voltage is provided by the ECM and common amongst all of the injectors (one output voltage for all injectors). The injector drivers provide a ground that is individual to each injector (one wire for each). So when I say I am missing the injector signal I am missing the D.C. voltage. I assume that this is a 5v signal but I don't know that for sure.
#25
Thread Starter
Junior Member
Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
Thanks for the pin-outs. I have one but it is different, more like a wiring diagram. I will put my O-scope on those pins tomorrow and see what I get.
#26
Senior Member
Joined: May 2012
Posts: 925
Likes: 5
From: Fort Erie, CANADA
Year: 1987
Model: Cherokee
Engine: 4.0
Thanks for the ideas. please keep them coming!
FYI, I just thought that I haven't checked the Park/Neutral safety switch. The next opportunity I get I will check the outputs of those pins and see if they are good. I am not sure exactly how this switch effects the spark but it has to be worth a try. If anyone has any information on this switch let me know.
.
FYI, I just thought that I haven't checked the Park/Neutral safety switch. The next opportunity I get I will check the outputs of those pins and see if they are good. I am not sure exactly how this switch effects the spark but it has to be worth a try. If anyone has any information on this switch let me know.
.
I'm going back to basics now. Focusing on what works. Do you have fuel pressure on the rail and the fuel pump is heard to prime when key is turned to RUN? MAP sensor tubing is good from throttle body to sensor? MAP sensor plugged in?
Also, do you have the "bible" on RENIX? Here's a link:
http://www.pirate4x4.com/tech/billav...ion_manual.pdf
Last edited by 67 GMC; 07-03-2017 at 06:26 AM.
#27
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 31
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
I haven't got to the sensor ground connections ....
Why not ???If sensor dont send correct signal to ecm maybe it cant send out a signal to fire....Cruiser ?
Why not ???If sensor dont send correct signal to ecm maybe it cant send out a signal to fire....Cruiser ?
#28
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
An excerpt from Tip 1:
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.
All the components listed below ground at the dipstick tube stud:
Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff.
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.
All the components listed below ground at the dipstick tube stud:
Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff.
#29
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 31
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Did see any mention of Map Sensor testing or replacement or I missed it. I am getting up towards Major in the years...lol..
#30
Thread Starter
Junior Member
Joined: Aug 2013
Posts: 90
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From: Petaluma CA
Year: 1988
Model: Cherokee
Engine: 4.0
The NSS switch shouldn't have anything to do with this and as far as I know there's no impact on spark. The switch just keeps the starter from engaging if the shifter is in any other gear but park or neutral. If it cranks when the key is turned to start in P or N, but doesn't crank in D, then it's most likely ok. There is a signal back to the ECU, but my manual says it only impacts idle.
I'm going back to basics now. Focusing on what works. Do you have fuel pressure on the rail and the fuel pump is heard to prime when key is turned to RUN? MAP sensor tubing is good from throttle body to sensor? MAP sensor plugged in?
Also, do you have the "bible" on RENIX? Here's a link:
http://www.pirate4x4.com/tech/billav...ion_manual.pdf
I'm going back to basics now. Focusing on what works. Do you have fuel pressure on the rail and the fuel pump is heard to prime when key is turned to RUN? MAP sensor tubing is good from throttle body to sensor? MAP sensor plugged in?
Also, do you have the "bible" on RENIX? Here's a link:
http://www.pirate4x4.com/tech/billav...ion_manual.pdf
The map map sensor is plugged in and functioning properly. I put a vaccuum in it just to see if it was in range and it was.