4x4 issues 2005 3.7
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Joined: Mar 2018
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It's possible. If the front and rear speed sensor are reading different, it will not allow the transfer case to shift into 4wd. Usually that also disables cruise control and has issues with the speedometer. But i have seen it where 4wd shifting is the only issue. You might want to grab the factory service manual (fsm) from the stickies at the top of the forum page and go through the steps to diagnose it. It might be as simple as a bad connection to a sensor, or just a sensor that needs to be replaced. If it's the sensor, it's just the one on top of the rear differential. Rockauto.com is a good place to buy parts and always looks for a 5% off coupon code before buying anything.
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Joined: Mar 2018
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And I just remembered something. The rear only has one sensor that reads speed off the tone ring attached to the ring gear. Some code readers will look for a rear left and right sensor, but they don't exist, so passenger rear abs sensor reading is not a thing. The abs module doesn't care about changing the sensors as long as they are reading something.
The front sensors are just a coil that gets excited by the wheel hub turning. As long as there is continuity in the circuit and a consistent signal from the turning of the hub, there will be no abs light coming on. I have had it happen where a worn bearing that had water ingress caused an intermittent abs that would kill the cruise control. I never tested 4wd with these conditions, but I'm confident it would not work due to the front sensor having issues.
For the rear sensor, it the same as the front. Any issue with the sensor can cause issues with shifting in 4wd, but not always show an abs light. I had to work on a 2006 3500 that would not shift out of 4wd. The speedometer would work, but the issue was the rear speed sensor. It would not shift out of 4wd because the abs sensors in the front and the speed sensor in the rear were reading different. Sometimes a failed sensor does not always read zero speed at a standstill.
Damaged wires at any point from the modules on the firewall to the rear differential can cause the issues as well. A slight nick in the wire insulation can cause corrosion that changes the resistance of the wire and causes unpredictable results.
The front sensors are just a coil that gets excited by the wheel hub turning. As long as there is continuity in the circuit and a consistent signal from the turning of the hub, there will be no abs light coming on. I have had it happen where a worn bearing that had water ingress caused an intermittent abs that would kill the cruise control. I never tested 4wd with these conditions, but I'm confident it would not work due to the front sensor having issues.
For the rear sensor, it the same as the front. Any issue with the sensor can cause issues with shifting in 4wd, but not always show an abs light. I had to work on a 2006 3500 that would not shift out of 4wd. The speedometer would work, but the issue was the rear speed sensor. It would not shift out of 4wd because the abs sensors in the front and the speed sensor in the rear were reading different. Sometimes a failed sensor does not always read zero speed at a standstill.
Damaged wires at any point from the modules on the firewall to the rear differential can cause the issues as well. A slight nick in the wire insulation can cause corrosion that changes the resistance of the wire and causes unpredictable results.
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From: Clayton MI
And I just remembered something. The rear only has one sensor that reads speed off the tone ring attached to the ring gear. Some code readers will look for a rear left and right sensor, but they don't exist, so passenger rear abs sensor reading is not a thing. The abs module doesn't care about changing the sensors as long as they are reading something.
The front sensors are just a coil that gets excited by the wheel hub turning. As long as there is continuity in the circuit and a consistent signal from the turning of the hub, there will be no abs light coming on. I have had it happen where a worn bearing that had water ingress caused an intermittent abs that would kill the cruise control. I never tested 4wd with these conditions, but I'm confident it would not work due to the front sensor having issues.
For the rear sensor, it the same as the front. Any issue with the sensor can cause issues with shifting in 4wd, but not always show an abs light. I had to work on a 2006 3500 that would not shift out of 4wd. The speedometer would work, but the issue was the rear speed sensor. It would not shift out of 4wd because the abs sensors in the front and the speed sensor in the rear were reading different. Sometimes a failed sensor does not always read zero speed at a standstill.
Damaged wires at any point from the modules on the firewall to the rear differential can cause the issues as well. A slight nick in the wire insulation can cause corrosion that changes the resistance of the wire and causes unpredictable results.
The front sensors are just a coil that gets excited by the wheel hub turning. As long as there is continuity in the circuit and a consistent signal from the turning of the hub, there will be no abs light coming on. I have had it happen where a worn bearing that had water ingress caused an intermittent abs that would kill the cruise control. I never tested 4wd with these conditions, but I'm confident it would not work due to the front sensor having issues.
For the rear sensor, it the same as the front. Any issue with the sensor can cause issues with shifting in 4wd, but not always show an abs light. I had to work on a 2006 3500 that would not shift out of 4wd. The speedometer would work, but the issue was the rear speed sensor. It would not shift out of 4wd because the abs sensors in the front and the speed sensor in the rear were reading different. Sometimes a failed sensor does not always read zero speed at a standstill.
Damaged wires at any point from the modules on the firewall to the rear differential can cause the issues as well. A slight nick in the wire insulation can cause corrosion that changes the resistance of the wire and causes unpredictable results.
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It's possible. If the front and rear speed sensor are reading different, it will not allow the transfer case to shift into 4wd. Usually that also disables cruise control and has issues with the speedometer. But i have seen it where 4wd shifting is the only issue. You might want to grab the factory service manual (fsm) from the stickies at the top of the forum page and go through the steps to diagnose it. It might be as simple as a bad connection to a sensor, or just a sensor that needs to be replaced. If it's the sensor, it's just the one on top of the rear differential. Rockauto.com is a good place to buy parts and always looks for a 5% off coupon code before buying anything.
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yeah, the problem is that it wont shift into 4x4
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Joined: Mar 2018
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That is the best working theory we had based on symptoms and fixes. The truck relies on reading from both the front and rear sensors to start shifting. If they have any issue or discrepancy it prevents shifting to protect the transfer case from damage due to binding.
Fsm 21-827: shifts will not take place with a wheel speed difference of greater than 13mph between the front and rear wheels.
Talking with other mechanics that deal specifically with programming vehicles, dodge trucks in the 2004 - 2010 Era are incredibly basic in the way they were programmed to work.
Like I said earlier, download the fsm and look at the diagnostic steps to get more details.
Fsm 21-827: shifts will not take place with a wheel speed difference of greater than 13mph between the front and rear wheels.
Talking with other mechanics that deal specifically with programming vehicles, dodge trucks in the 2004 - 2010 Era are incredibly basic in the way they were programmed to work.
Like I said earlier, download the fsm and look at the diagnostic steps to get more details.
Last edited by Hesselhoff; Jan 29, 2025 at 02:54 PM.
Professional
Joined: Mar 2018
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A few things to try, check the fluid level in the transfer case. If you can read data from individual abs sensors, check the front left wheel sensor while driving. Unplug the abs sensor and check for continuity in the sensor. Use a known good battery and disconnect the one in the truck. Recheck the fuses. The fsm should have data on what angle is needed to disengage the transfer case. Try disengaging by hand when the truck is off at least two wheels.
If it turns out you have a faulty front abs sensor it will not throw a code until the abs needs to function, or the sensor data is needed to control something. It mat be easier to replace the entire wheel hub than replace just the sensor.
If it turns out you have a faulty front abs sensor it will not throw a code until the abs needs to function, or the sensor data is needed to control something. It mat be easier to replace the entire wheel hub than replace just the sensor.