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  #256  
Old February 26th, 2018, 18:47
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zluster zluster is offline
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Re: Project CRD MJ is born:

Tested the TJ gauge cluster finally!
https://www.youtube.com/watch?v=xpO4isRTThs

However I thought the KJ plugs were the style I needed but it turned out they have more pins than the TJ, so I need to find the same connector type but with fewer pins to fit the TJ cluster.

Grrr, back to the junkyards to raid 15 year old Chryslers.
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  #257  
Old February 27th, 2018, 13:09
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Re: Project CRD MJ is born:

I will need to do some more testing in the future where I read through the OBDII port with a scanner to show what PSI to oil pressure sensor is seeing, and how that translates to the position on the TJ guage cluster. The TJ cluster is reading oil pressure through the PCI bus from the ECU, and then displaying that as an analog value. The question comes up as the the calibration, when it read "half" what PSI was that? When it went higher to 3/4 what PSI was that?

If you noticed the oil pressure gauge is the only one that does not have any units shown. This is because on the 2002+ TJ the oil pressure gauge is basically just an idiot light! The sensor on the newer TJ is a discrete, meaning it is either open or closed. In theory, when off or no pressure the switch is open circuit, and then when the engine is on and oil pressure is "good" it is closed. This way if your oil pressure drops below "good" or if it fails it should go open circuit. What the TJ ECU does is read this open or closed switch and send a value to the cluster. So the TJ cluster reading from the ECU only sees 0 PSI/bad, or X PSI/good. This means that on a stock TJ the oil pressure gauge either shows zero, or middle. Since the gauge is then basically just an idiot light they removed the units of measure.

However since the CRD ECU does read an analog pressure from the oil pressure sender the REAL psi is transmitted over the PCI bus, and since the TJ cluster is reading a real analog value it drives the gauge accordingly. The only thing left for me is to determine exactly what pressure the middle means, and exactly what pressure the high means.

I am working on a way to read the calibration from the processor onboard, which may allow me to change the scaling factor on the gauge. Likely that will be much further along, I'm just happy the Main functions, fuel level, coolant temp, RPM, and presumably speed all read correct.

In final form this will be wired into the normal dash wiring for the cluster for all functions such as turn signals, lights, 4wd indicator, etc, leaving the obdii port completely open like factory.
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  #258  
Old February 28th, 2018, 16:46
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Re: Project CRD MJ is born:

My coworker came over last sunday to use my pressure washer on his newly acquired wildernest to get it cleaned up, I decided it was a good time to open mine and take a look inside the back of the MJ........I'm find all sorts of parts I forgot where back there.







Fun times ahead! Looking forward to having both MJs out and be camping!
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  #259  
Old February 28th, 2018, 16:48
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zluster zluster is offline
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Re: Project CRD MJ is born:

Tested the TJ gauge cluster finally!
https://www.youtube.com/watch?v=xpO4isRTThs

However I thought the KJ plugs were the style I needed but it turned out they have more pins than the TJ, so I need to find the same connector type but with fewer pins to fit the TJ cluster.

Grrr, back to the junkyards to raid 15 year old Chryslers.


I will need to do some more testing in the future where I read through the OBDII port with a scanner to show what PSI to oil pressure sensor is seeing, and how that translates to the position on the TJ guage cluster. The TJ cluster is reading oil pressure through the PCI bus from the ECU, and then displaying that as an analog value. The question comes up as the the calibration, when it read "half" what PSI was that? When it went higher to 3/4 what PSI was that?

If you noticed the oil pressure gauge is the only one that does not have any units shown. This is because on the 2002+ TJ the oil pressure gauge is basically just an idiot light! The sensor on the newer TJ is a discrete, meaning it is either open or closed. In theory, when off or no pressure the switch is open circuit, and then when the engine is on and oil pressure is "good" it is closed. This way if your oil pressure drops below "good" or if it fails it should go open circuit. What the TJ ECU does is read this open or closed switch and send a value to the cluster. So the TJ cluster reading from the ECU only sees 0 PSI/bad, or X PSI/good. This means that on a stock TJ the oil pressure gauge either shows zero, or middle. Since the gauge is then basically just an idiot light they removed the units of measure.

However since the CRD ECU does read an analog pressure from the oil pressure sender the REAL psi is transmitted over the PCI bus, and since the TJ cluster is reading a real analog value it drives the gauge accordingly. The only thing left for me is to determine exactly what pressure the middle means, and exactly what pressure the high means.

I am working on a way to read the calibration from the processor onboard, which may allow me to change the scaling factor on the gauge. Likely that will be much further along, I'm just happy the Main functions, fuel level, coolant temp, RPM, and presumably speed all read correct.

In final form this will be wired into the normal dash wiring for the cluster for all functions such as turn signals, lights, 4wd indicator, etc, leaving the obdii port completely open like factory.
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  #260  
Old February 28th, 2018, 16:48
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zluster zluster is offline
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Re: Project CRD MJ is born:

I made some progress on the TJ gauge cluster, I cannot seem to program less than 1000 miles, I suppose thats close enough to zero? I was just really looking forward to seeing it run up from zero. I might keep playing with it, I also want to figure out to reprogram the VIN.

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  #261  
Old March 2nd, 2018, 21:55
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zluster zluster is offline
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Re: Project CRD MJ is born:

Wiring work continues on the main engine harness:





Auto trans stuff removed:


I gotta start sitting down the with the Xj wiring diagrams and the KJ wiring diagrams to see what I can adapt from one to the other, and what I need to add, like glow plug relays. etc.
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