Atrac not engaging help?

[J1000]

Real time help needed. Drove out to Moab from TN. We did the 4x4 trail at Arches today and got in a snow covered off camber situation. Had front passenger tire off the ground and one rear tire spinning also. Abs light came on, vsc off and trac light also on. I never felt the braking shuddering feeling of a trac engage like I have before. I backed down and tried the obstacle like 4-5 times still nothing and expected it to engage. Whole time I was in 4 lo on t case and low on the transmission. I pushed the center diff lock and then picked a different line and we got up. Abs, vsc off, trac light stayed on the whole time and only went off after we got off the trail and I turned off the truck back in town. When I re started it all lights went off and dash lights back to normal. I have my fsm, my tools, and my fluke meter, no tech stream, and unfortunately forgot my scanner. We are only here 1 more day so will probably stick to some easy trails but any help would help appreciated.

Jason

You are doing it wrong you should have the center diff locked before you get in a situation where the wheels are off the ground.

 

[NOSAJ]

Regardless of it I’m doing it wrong or not Shouldn’t a-trac work regardless of the center dif lock? It never engaged in my situation with the dif lock on or off. I tried the harder line with diff lock engaged and nothing. Only able to get up because I picked a different line.

Abs light was on and seems like something not right. So trying to troubleshoot the situation

 

[J1000]

Regardless of it I’m doing it wrong or not Shouldn’t a-trac work regardless of the center dif lock? It never engaged in my situation with the dif lock on or off. I tried the harder line with diff lock engaged and nothing. Only able to get up because I picked a different line.

Abs light was on and seems like something not right. So trying to troubleshoot the situation

It might try to work but would be unable because an open center diff allows much more movement of the front and rear diffs independently. So it might literally not be able to get the clamping force needed at each axle.

A-Trac only works because of how differentials function.

You didn't pull any codes so your statements about having multiple lights on the dash is meaningless because those lights could all have come from a leaking gas cap.

I'm picturing your truck tetering on 2 wheels with an open diff, so as A-Trac clamps down on the front wheel that's in the air to get the front wheel that's on the ground moving forward, the torque is unloaded through the transfer case to the rear axle. Same thing with the rear axle unloading to the front. It's possible A-Trac was moving so much fluid trying to brake all 4 wheels that it ran out of pressure or overheated which caused the light to come on.

 

[100s]

Hey guys I have an 01 lc and for the life of me can not get the tires to slip on anything. It def feels like 4wd is being engaged but still haven’t heard the atrac “beep” or seen the light. I know the light works because it comes on when I start the truck but my question is aside from crawling up a mountain are there any surefire ways to test my atrac system or trigger it manually? I want to know that it works so I don’t have to find out the hard way. Thanks boys.

Mack,

If you look over on my thread. My 06 doesn't flip any lights on when the transfer case is in low. When I engage the CDL I do get VSC OFF as expected. But on an icy hill when wheel spin is encountered the 06 does engage ATRAC I do get the trac light and I can hear the ABS engaging. This behavior is exactly the same regardless of the transfer case gear (H/L)

In my 02, as soon as I put the Transfer case into L (without the CDL) I get ABS, VSC OFF and VSC trac and I do NOT get the ATRAC light or ABS noises in Low range.

Sadly, the 06 climbed the ice 2x better than the 02, the 02 has rugged terrain tires and the 06 has Mich Defender LTX2's. I attribute this to ATRAC being able to engage with the CDL in L range.

Time to pull codes

-m