Front axle not engaged?

Issues pertaining to the TGB/C30X series engine and driveline issues
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thedoeges
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Location: Castle Rock, Colorado

Front axle not engaged?

Post by thedoeges » Fri Apr 01, 2016 11:35 am

I am not sure if my front wheel drive is working. Although the light is on when I push the button, and the steering feels heavier (hard to say), the rear wheels are spinning faster than the front wheels. The question is: Do the front and rear axles rotate at a different speed in all wheel? It might also be that the actual front wheel drive is not engaging, despite the fact that the vacuum sound is heard when pushing the button. If that is happening I would not know why? Also, the way I read the manual, if there were a leak, it would default to all wheel, is that correct? Any ideas on troubleshooting and where to look first?

Thanks.

Marcus

roobar_and_custard
Australia
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Location: Melbourne, Australia

Re: Front axle not engaged?

Post by roobar_and_custard » Wed Apr 06, 2016 1:31 am

Hi.
Front and rear axles should spin at the same speed - if they don't the diff ratios are stamped on a metal plaque on the diff housing.
Ratio for your's should say 2.91 (TGB11) I think, but could be 3.44 (TGB13), or 3.66 (TGB20).

A failure in the transfer case vacuum will set the system to 4x4 as a fail safe, and the dog clutch gets engaged by a spring in the diaphragm housing.

Mine was stuck in 6x6 when I got it, due to a split diaphragm, and I drove it for ages before I realised. Mind you, all my axles rotated at the same speed...

Good luck.
Ian

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Wed Apr 06, 2016 9:36 am

Thank you Ian. The issue is, that it will not engage in 4 wheel with the front axle. I thought that 4 wheel is the fail safe default, yet it is not powering the front wheels when 4 wheel is turned on.

Marcus

roobar_and_custard
Australia
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Location: Melbourne, Australia

Re: Front axle not engaged?

Post by roobar_and_custard » Wed Apr 06, 2016 6:02 pm

I'm not an expert, but I would jack up one of the front wheels so you can spin the transfer case front output using this wheel. In theory, with the engine off (no vacuum), the cross axle diff lock will be "open" and the transfer case will be "locked" - therefore the wheel won't spin. You may need to relieve any residual vacuum pressure before checking as the chassis has two vacuum reserve tanks which will hold pressure for a period of time.
If the wheel rotates with no vacuum, then the transfer case is "open" and you have a problem.
If it doesn't - you will also need to check that the cross axle diff lock is "open", which you can do by lifting the other front wheel - that should then spin in reverse direction when you rotate the original front wheel.
The actuator on the transfer case is easy to access by opening the vacuum actuator and removing the diaphragm - you could check this is working by manually cycling it.

Good luck. :)

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Mon Apr 11, 2016 9:56 am

Thank you all for your responses, here and via PM. The issue was that the VTG needed adjustment, as the nuts that help the membrane move the pushrod were not tightened after all those years. Lucky, that was a cheap fix.

gufesd
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Location: san diego, ca

Re: Front axle not engaged?

Post by gufesd » Sat Aug 26, 2017 2:40 pm

Hello Everyone,

Would having the "Brake Light" on keep the front axle from engaging? I have tried to pull out the pin on the top of the brake pedal, but the light is still on. The solenoid seems to click every time I depress the 4wd button, but the front axle does not engage. It used to work before I changed both front CV boots. Any help would be appreciated.

Thanks.

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Sat Aug 26, 2017 3:22 pm

It should have nothing to do with the front axle engagement. There is a brake sensor that needs to be reset. I had to deal with that after I bled the brakes to exchange the axle boots. Forgot exactly where it is located, but there are good diagrams on www.c303.de. It will extinguish the brakes light.

gufesd
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Location: san diego, ca

Re: Front axle not engaged?

Post by gufesd » Sat Aug 26, 2017 3:53 pm

The vacuum seems to work as I hear the hissing when disengaging the lockers.

Uli-RT
Germany
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Re: Front axle not engaged?

Post by Uli-RT » Sun Aug 27, 2017 4:24 am

There is another switch in the engineroom.
Left side of the kabine is the "brakepreasuredifferenceswitch".
Pull the cable off, turn the switch out (plastic) than in again, calbe on, ready.
Lie under the car. Best way to see and reach it.

gufesd
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Location: san diego, ca

Re: Front axle not engaged?

Post by gufesd » Sun Aug 27, 2017 1:01 pm

The brake light now turns off! Thanks for the tip Uli-RT. Now, if I can just figure out why the front axle is not engaging.

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Sun Aug 27, 2017 1:10 pm

Thanks Uli, that's the reset I was talking about

gufesd
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Location: san diego, ca

Re: Front axle not engaged?

Post by gufesd » Fri Oct 27, 2017 6:28 pm

Can anyone please let me know where I can purchase another solenoid for the 2wd/4wd system? It is the solenoid located under the rear facing jumpseat on the passenger side. I am unable to source one out, because I don't know what to look for and where.

I have already fixed the rust on the diaphragm located on the transfer case. I cleaned the solenoid from all sorts of gunk, but now the magnet does not pick up the pin when the engine is running. The solenoid works fine when just the ignition is on, not when the engine is running. When I block the vent, everything works fine. I am deducing that the magnet is failing???

I don't want to deal with it anymore, might as well get another solenoid or another switch altogether. Any help or links to the solenoid would be a great help. Thanks again for the help.

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Fri Oct 27, 2017 6:33 pm


gufesd
Posts: 21
Joined: Mon Aug 25, 2008 11:09 pm
Location: san diego, ca

Re: Front axle not engaged?

Post by gufesd » Fri Oct 27, 2017 6:53 pm

I looked there, but I could not find the actual part. Do you have a link to the actual part? I don't even know what you would call it? I searched for "solenoid" and "vacuum", but no luck. Thanks again.

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thedoeges
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Re: Front axle not engaged?

Post by thedoeges » Sat Oct 28, 2017 8:24 am

Claes at Tatanka knows a lot. Maybe send him an email. He has helped me many times.

It's

info@tatanka.nu

Good Luck!

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