D40 4WD Light Flashing on Dash. Weird

[Dwayno44]

Hi All,

This morning I got in my Navara to drive it to work and found it was running quite strangely. It wasn't changing gears until very high revs and was jumping back down gears as soon as I slowed. Gear changes were very violent.

My first reaction was something must be wrong with the clutch/box. Then I identified the 4wd light flashing on the dash. I stopped at the next set of lights and tried to fiddle around with the 4wd switch, with no luck.

I had to pull up and try shutting the car down, putting it in and out of gear multiple times and attempting to turn the knob again and again. Still no luck.

When I put it into 4wd, all wheels and the shaft go solid on the dash. When I switch back to 2wd, the rear wheels are solid but the shaft and front two wheels flash.

Is there some trick that I am missing here?

 

[Panuara]

The flashing is telling you that the servo is rotating still ( probably a more technical explanation) it should take less than a minute when idling and out of gear for it to change back to 2wd.

 

[Old.Tony]

As above.

What's happening when you hit the switch (assuming a start at 2WD) is a servo rotates a mechanism in the transfer case by 90 degrees, which slides a gear into place to engage the chain that links the front and rear drive shafts. If you continue to 4LO (and meet the neutral+brake requirement), the servo rotates a further 180 degrees which changes gears in the transfer case from 1:1 to about 2.6:1.

During the entire process, sensors (probably just switches) determine whether or not the appropriate mechanisms have moved as demanded. These sensors are relied on by the transfer control circuit - and pass the info on to the cluster to let you know what's happening.

If the front axles are flashing, it's usually in 'wait' mode (and there's a sensor for that too) while the servo does its thing. If it continues flashing then it's either a bad sensor, or the servo has failed to make progress.

Issues with the transfer case are more often than not electrical - poor connection caused by debris or oxidisation of the contact surface. Unplugging them or plugging them in again will help shift both, and thus remove that from the range of possibilities.

Inside, the switches could be erratic and some people have had problems with these. Servos can fail too.

To check the servo, just remove it from the transfer case and have someone activate the switch - the servo should turn obediently. Return the switch to 2WD and make sure the servo turns back - do not reinstall just yet.

With the servo removed, use a large screwdriver and turn the mechanism inside. You should be able to feel the various things engaging as described above as you rotate the gear through 270 degrees. Don't forget to turn it back!

If the servo doesn't obey, you could use a multimeter and check for an input signal. www.niss4x4.com.au should be able to get you one rather inexpensively. If the servo is moving and the mechanism inside turns but not completely, it might be time to crack the transfer case open.

 

[Busiboy]

Mine flashed when an abs sensor died but I had all sorts of other lights going as well.

 

[Dwayno44]

Thanks guys. Wow Tony, you never fail to provide awesome advice.

So I spent a few hours after work fiddling around and made a little bit of progress but not as much as I would have liked.

I took the actuator off and found that the shaft is not spinning when the 4wd button is pressed in the cab. This would lead me to believe it's a sensor/electronic fault. Also worth noting is that when I press the brake pedal in the car I can hear an audible click from the lower central section of the dash - ie near the 4wd button.

For now the car is in 2wd. I managed to manually change it and took the accumulator apart to realign the shaft.

Any tips on how to proceed from here. I want to check the electronic side of things - maybe starting with the relay given I can hear a clicking noise. How do I check the relay?

 

[Old.Tony]

Relays for the transfer case are in the IPDM/ER box (the black box behind the battery). There should be two relays and they should click as the selector is changed. There might be some fuses too - I'd have to pull the manual out and look but the wife wants to race to the shops in a minute so I can't hang around and have a good read.

 

[Dwayno44]

I'm not too keen on turning the switch in case it tries to engage 4wd again and I can't get it back. Just seems strange to me that the click occurs whenever I touch the brake (one of the conditions that has to be met before it'll shift)

 

[Old.Tony]

You can always pull the servo out and manually pull the thing back to 2WD mode. You could just pull the relays and clean the contacts anyway (fuses too). I doubt the 4WD light would go out until you tried to engage/disengage 4WD mode and the sensors figured the box was moving properly.

 

[Dwayno44]

Okay. How do I test the relay if I take it out to clean it?

Also, how do I go about testing the signal to the actuator?

 

[longy509]

Hi mate probably not related at all but the only time my 4X4 light flashed i had snapped my front cv axle

 

[Dwayno44]

Thanks longy. Yeah I don't think that's the issue here. It was clearly engaged in 4wd the other day. Could definitely see how driving it round like that would cause that to occur in a hurry though

 

[Old.Tony]

You don't test it when it comes out, all you're doing is cleaning the contacts. If that's what the problem was, when you reinsert the relay it'll start working again. The relays are fairly robust and I don't recall one failing. Recall plenty of dirty contact issues.

 

[Dwayno44]

Sorry to bump this one up, but the issue is still ongoing.

I ended up trying the 4wd switch again which alerted the system that the car was back in 2wd - now revving and driving properly. Problem is the yellow 4wd light is on, solid. Everytime I start the car I get a flashing black and white 4wd symbol, then the yellow 4wd light comes on. This tells me its testing the 4wd sensors and not getting the feedback it wants.

My reading has lead me to believe it may be one (or all) of the 3 switches on the transfer case that's causing the issue. This seems to be a fairly common fault as the switches corrode due to water ingress. I followed the approach by a number of the UK guys and cut the switches open. Unfortunately I didnt see the obvious signs of corrosion I was hoping for. I gave them a clean up, and glued back together with araldite. I'm going to leave them to set overnight. Looking forward to changing the transfer case oil and giving it a go. Fingers crossed.