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XX88 series Sentry wiring diagram


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I wanted to post the factory wiring diagram for the 88 series sentry system .

I am pinpoint testing my system to ensure I don't have an issue that isn't the actual module (my sentry light is coming on for the low /odd side gears)

I was unable to find a factory schematic online , so I was able to take a picture of the schematic from my local dealer . 

Just wanted to get this resource up for anyone else looking to check things .

this picture is of the early system AFTER dealer updates . The newer system is the same as the one pictured , the early system has a different clutch switch , and I was told they have all been updated to this .

the solenoids ohm out around 2.5 ohms . The pressure switches are normally closed . 

The system operation seems pretty basic , the hi/low switch located on the lever , tells the module which mode has been selected , the module then applies power to the solenoid for the range selected , and removes power from the other . It then looks for the pressure switch signal , the one coming on must open , while the one coming off must close . 

If your system has failed in a way where the tractor won't move , or bound up in both ranges at once , I think you could simply apply power to the solenoid , hi or low not both to get it to move enough to get it home or in the shop . (This advice is not professional , try at your own risk)

but if you're able to read the schematic and follow along , you should be able to form your own opinions .

I think building building your own with time delay relays or a programmable Plc board would be pretty straight forward . I have read the threads on the ideas and build on this forum . However , I have not seen anyone say what the actual time delays are . I:E what is the delay for the off going solenoid so as to not shock load the system? Is it .5 , 1, 1.5 seconds ?

if anyone has this info , or is able to test their working system and report back , I think that would be very helpful .

 

image.jpeg

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16 hours ago, Driveline651 said:

I wanted to post the factory wiring diagram for the 88 series sentry system .

I am pinpoint testing my system to ensure I don't have an issue that isn't the actual module (my sentry light is coming on for the low /odd side gears)

I was unable to find a factory schematic online , so I was able to take a picture of the schematic from my local dealer . 

Just wanted to get this resource up for anyone else looking to check things .

this picture is of the early system AFTER dealer updates . The newer system is the same as the one pictured , the early system has a different clutch switch , and I was told they have all been updated to this .

the solenoids ohm out around 2.5 ohms . The pressure switches are normally closed . 

The system operation seems pretty basic , the hi/low switch located on the lever , tells the module which mode has been selected , the module then applies power to the solenoid for the range selected , and removes power from the other . It then looks for the pressure switch signal , the one coming on must open , while the one coming off must close . 

If your system has failed in a way where the tractor won't move , or bound up in both ranges at once , I think you could simply apply power to the solenoid , hi or low not both to get it to move enough to get it home or in the shop . (This advice is not professional , try at your own risk)

but if you're able to read the schematic and follow along , you should be able to form your own opinions .

I think building building your own with time delay relays or a programmable Plc board would be pretty straight forward . I have read the threads on the ideas and build on this forum . However , I have not seen anyone say what the actual time delays are . I:E what is the delay for the off going solenoid so as to not shock load the system? Is it .5 , 1, 1.5 seconds ?

if anyone has this info , or is able to test their working system and report back , I think that would be very helpful .

 

image.jpeg

I would also stick a pressure gauge on it so not to damage transmission if pressure gets low, that is why the sentry was designed for

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  • 3 weeks later...

Update I wanted to confirm that the side not working (low side)on my tractor was capable of working , and that the sentry was not adding power to the solenoid , and was properly removing power from the side that was working (high side) when I selected the other .

I clamped on a power probe to the blue wire going to the high solenoid , and as expected the sentry added 12v when the high side was selected and removed 12v when the low side was selected .

moved power probe tester to the other blue wire that goes to the low side solenoid , showed no power no matter what I did with the lever or clutch , meaning the sentry was not adding power to the low side , but it was removing power from the high side . Having manually actuated both high and low solenoids previously and watched the new pressure switches operate properly I was fairly confident that the wiring, solenoids,pressure switches were all functioning properly . 

So I added 12v to the wire going to the low side solenoid with the power probe and the tractor moved in the low side confirming that it was a bad sentry . (I was sure not to wiggle wires or tug on things during this process) 

But , here is the weird part , the sentry kept power to the solenoid after I stopped applying power with the probe ! Ithen moved the lever to the high side and it went to High , no volts showed on wire to low solenoid as it should , selected the Low side and IT SHIFTED to the low side , showing 12v on the wire again ! 

I disconnected the power probe and ran the tractor up and Down the road for about 30 minutes , shifting it through all the gears , and HIGH /LOW at least fifty times it stayed working ... 

I'm not sure what adding power to that wire did to the module to make it start working , but I hope it stays working !

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46 minutes ago, Driveline651 said:

Update I wanted to confirm that the side not working (low side)on my tractor was capable of working , and that the sentry was not adding power to the solenoid , and was properly removing power from the side that was working (high side) when I selected the other .

I clamped on a power probe to the blue wire going to the high solenoid , and as expected the sentry added 12v when the high side was selected and removed 12v when the low side was selected .

moved power probe tester to the other blue wire that goes to the low side solenoid , showed no power no matter what I did with the lever or clutch , meaning the sentry was not adding power to the low side , but it was removing power from the high side . Having manually actuated both high and low solenoids previously and watched the new pressure switches operate properly I was fairly confident that the wiring, solenoids,pressure switches were all functioning properly . 

So I added 12v to the wire going to the low side solenoid with the power probe and the tractor moved in the low side confirming that it was a bad sentry . (I was sure not to wiggle wires or tug on things during this process) 

But , here is the weird part , the sentry kept power to the solenoid after I stopped applying power with the probe ! Ithen moved the lever to the high side and it went to High , no volts showed on wire to low solenoid as it should , selected the Low side and IT SHIFTED to the low side , showing 12v on the wire again ! 

I disconnected the power probe and ran the tractor up and Down the road for about 30 minutes , shifting it through all the gears , and HIGH /LOW at least fifty times it stayed working ... 

I'm not sure what adding power to that wire did to the module to make it start working , but I hope it stays working !

im not sure how intelligent these sentry's are but it reminds me of removing power from ANY electronic device and resetting it - maybe that is what happened ? 

removing the battery power to the tractor overnight might have done the same thing  ? 

 

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1 hour ago, searcyfarms said:

im not sure how intelligent these sentry's are but it reminds me of removing power from ANY electronic device and resetting it - maybe that is what happened ? 

removing the battery power to the tractor overnight might have done the same thing  ? 

 

I added power to the wire the module should output power to the solenoid . I wasn't on the power or ground input side to the module .

I also believe that depressing the clutch resets the sentry , and I have had this module out overnight in order to perform all of the other testing . I wish it would have fixed it just by removing power .......

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31 minutes ago, Delta88 said:

So are you bypassing the sentry power harness and going directly to the solenoids with a jumper wire?

I did that previously while watching the pressure switches with a volt meter . 

This was with the sentry hooked up and used a power probe tapped into the wires going from sentry to solenoids , bl/wt and bl/Blk 

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Sounds like I am having a similar problems. Mine is stuck in the high side; with no power going to the low solenoid. Going to try a new pressure switch but the sentry seems to be working.

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16 hours ago, Delta88 said:

Sounds like I am having a similar problems. Mine is stuck in the high side; with no power going to the low solenoid. Going to try a new pressure switch but the sentry seems to be working.

Yes mine only worked on the high side , and if I selected the low side the sentry light would immediately come on . 

I checked all powers and grounds , added a ground as per the update , verified cab to chassis ground good ( cab is isolated)

checked micro switch and wires for proper operation . 

I had replaced the pressure switches with updated style (no help) 

I then disconnected the sentry , ohmed out solenoids , and then installed an ohm meter on the switch and while monitoring the switch added 12v to the corresponding solenoid with tractor running in neutral . Confirmed the solenoid allowed enough pressure to open the switch , then did that on the other side . (Only one side at a time so you don't engage high and low at the same time)

I then ohmed any other wires in the system to confirm no shorts or opens.

i was then confident that the sentry was bad . I reassembled the tractor and reinstalled the sentry and tested it with no change ( a guy can hope)

A week or two later  I hooked up the power probe and added power to the low side solenoid with everything hooked up , and it somehow woke up the module .

if you conclude that your sentry is bad , I would suggest you try adding power like I did ( confirm low side selected an no power going to high side solenoid prior) and add 12 v to the wire going from sentry to low solenoid while everything is hooked up . Mine might have been a fluke , but it worked for me ... Might work for you , who knows.. 

If you try it , please report back with your results either way please .

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When you added power to the low side solenoid ( causing the sentry to come alive) did you have it unplugged and were using a jumper wire off a battery? With a jumper also to a good ground location?

My sentry is getting power from both sides of the harness; Plug A on the male side with power going to the sentry light via plug C; and plug E has power going to the switch.

The female side of the harness has power on the A plug. So power going into the sentry isn't the problem.

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