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Cat 725 E329 code

Hunter013

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There is no filter head on this tranny. The filter fits right into the bottom of the trans. If that makes sense.
 

Hunter013

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Sorry, should have been clearer. I meant the head of the bypass valve. It's mounted on to the housing with 4 bolts from what I can see.
Understood. I’ll try to get it apart today
 

Nige

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Here's something it might pay you to check - electrical continuity. Thanks @ahart for the suggestion.

At the filter bypass switch you have a 2-pin connector with brown wire and a black wire. Open that connector and check: -
1. continuity to machine frame ground on the black wire #202. You should read resistance of 5 ohms or less.
2. Unplug connector J2 on the powertrain ECM and check continuity of the brown wire #426 between the 2-pin plug on the machine harness next to the filter switch and Pin 29 on connector J2. NOTE: Wire #426 goes through a number of major harness connectors between the location of the filter and the ECM.

I'll send you the electrical schematic. It will make it easier.
 

Nige

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Looking at the electrical schematic the alarm sounds when Pin 29 on connector J2 of the ECM is connected to machine frame ground. If you have a chafe in the harness somewhere between J2 and the switch that is maybe rubbing where it passes through a P-clip or has rubbed through on the transmission case that would give a short circuit to ground and trick the ECM into thinking that the filter was plugged.
 

Chrisso

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If you have a chafe in the harness somewhere between J2 and the switch that is maybe rubbing where it passes through a P-clip or has rubbed through on the transmission case that would give a short circuit to ground and trick the ECM into thinking that the filter was plugged.
That's exactly what I was thinking. So could moisture in an electrical connection, or oil.

Also, just out of curiosity, at what transmission oil temperature does that event become active? If you get an E329 before the trans temp reaches the temps mentioned below, you have an ECM fault.

1686443299165.png
 

Nige

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Something you could try as a quick & dirty test.
When the alarm is going off with the enging running, go under the machine and disconnect the 2-pin Deutsch connector right next to the plugged filter switch.
If the alarm stops then the cause must be that the bypass spool has moved to one side and operated the plugged filter switch.
If the alarm does not stop you have a wiring harness or ECM fault.
 

Hunter013

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Also, just out of curiosity, at what transmission oil temperature does that event become active?
124F

If the alarm does not stop you have a wiring harness or ECM fault
Pulled the connector and the alarm stayed on. Wish I thought of that before.

I will check wiring. I’ll post what I find. Thank you everyone for the help.
 

Nige

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Wish I thought of that before.
You’re not the only one…..
TBH the penny didn’t drop for me until I looked at the electrical schematic and saw how the switch operated.

IIRC the wires pass through a number of harness connectors between the one next to the switch and the ECM. It might pay you to find and open every connector then test the wire in sections.
 

Chrisso

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IIRC the wires pass through a number of harness connectors between the one next to the switch and the ECM. It might pay you to find and open every connector then test the wire in sections.
Thinking one step further than this you could just pull the applicable wire out of the ECM. See if it stays on. At this stage I'd be cycling the isolator between troubleshooting steps. Not sure why, just a feeling.
 

Hunter013

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Head Floor Sweeper
t might pay you to find and open every connector then test the wire in sections
Checked everything in sections and it all checked out. What else could there be to check? ECM?
 

Hunter013

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With everything connected, I checked from the switch connector to chassis ground and both wires showed continuity. I'm assuming the hot wire shouldn't be grounded.
 

Nige

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I'm assuming the hot wire shouldn't be grounded.
There isn’t a “hot wire” per se. The ECM “looks” for ground on the wire to the switch. As you know the other wire from the switch is connected to ground, so if the ECM detects continuity to ground from Pin # whatever-it-is, and at the same time the transmission oil temperature is above 51DegC the alarm should sound.

All I can suggest is to re-iterate what Chrisso posted somewhere above. Get a Deutsch connector pin removal tool and at the ECM plug remove the wire that connects the ECM to the plugged filter switch. If the alarm continues to go off with that wire removed (provided that temp conditions are met) then an internal problem in the ECM is the only possibility that I can see.
 

Nige

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Apologies are due again……
Unfortunately it seems like a recurring theme regarding this problem.

Working through an issue with another machine we have discovered that there is an issue regarding how the electrical schematic is drawn which turns the whole operation of the plugged filter switch on its head.

The switch contacts by design are Normally Open as confirmed in the illustration below. However because the switch is of the proximity type then when it is installed and the business end of it comes into contact with the bypass spool the presence of the metal spool will cause the switch contacts to close. That explains how it works but the way that the schematic is drawn is confusing by showing the contacts open and leading to the assumption that the switch closes to activate the alarm.

Try installing a jumper wire between Pins 1 & 2 of the machine harness connector for the plugged filter switch. Does the alarm stay off or come on.?
 

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Chrisso

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Good pick up Nige.

Try installing a jumper wire between Pins 1 & 2 of the machine harness connector for the plugged filter switch. Does the alarm stay off or come on.?
And if that doesn't reveal the fault do the same thing at the ECM
 

Hunter013

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I put everything back together, parked it for a few days, came back today, warmed it up and drove it around. Now no alarm. I'm going to try it again tomorrow and see what happens.
 
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