Know How. Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.
Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. A flashing indicator light is typically caused by wiring or an electrical component like the controller, a faulty motor or fork, a speed sensor, or a position switch.
Many 4WD units have an actuator located on the front axle to lock and engage the front axle for 4WD. If this actuator or its shift fork is faulty, the vehicle will remain in 2WD, and the light will flash, indicating a problem to the driver. Check to see if the vehicle is in 4WD.
Typically, if the vehicle does not have a locking differential and did not complete its shift into 4WD, the front tire should spin freely. Jack up the one side of the front of the vehicle and spin the tire. Thanks in advance - jim. The blinking light means something is not engaging or the 'puter doesnt see that its engaged. Most commonly its the front axle actuator stuck or one of the vacuum lines came off. When its on and blinking can you shift into low range?
If so then the xfer case actuator is working. Then you need to verify the front is actually fully engaging. I know of 1 4wd system 'puter that went bad. Wasnt seeing the signal from the xfer case that it was locked in so wasnt sending the signal to lock in the front axle. Could shift into low range but was 2wd low. Thanks for the quick reply!
Yes the 4 hi and lo work fine. I'll check it out tonight. Sorry to just jump into the convo, but I am having a similar problem. I had my Rodeo lifted last year by a shop that is now out of business. Ever since I got it back, my 4WD light flashes constantly. I have tried looking for vacuum lines that have come loose near the firewall, but I have nothing to compare it to. There are a few small hoses that aren't connected, but I don't know if that's normal there aren't any other items that are close enough to hook them up to it.
I tried resetting the ECU already Thanks in advance for the help! We need vehicle info first, like what year. They used different methods in different years. If the light is still blinking when you shift to 2 wd then you are still at least partially stuck in 4wd.
Thats not good, you could bind and break things. Its a 5spd. I hope you're wrong about the truck not coming out of 4WD, I've probably put on about k miles since its been doing that. With it in 2wd try putting it into low. If it moves more then just a little bit then your t-case actuator isnt working and you are locked in 4wd.
If not then the problem is probably at the front axle. There are 2 vacuum lines on the actuator you can see it on the drivers side under the vehicle without removing the gravel pan.
One should have vacuum on it in 2wd and the other should have vacuum in 4wd. If not then either the vacuum switching solenoids are bad or a vacuum hose is loose somewhere and not getting vacuum to the solenoids. If the vacuum on the front axle actuator is ok then the actuator might be stuck. You should be able to remove it and get it sliding again. There are also sensors on the actuators that might be bad or have a broken wire making the system think its still locked in.
Or the 4wd computer could be bad but I dont know what symptoms a bad computer would cause. I only know of one computer that has gone bad and it caused the front axle to not lock in at all. Thank you very much for your quick and informative replies! I don't really know a lot about cars, so I ordered a repair manual today so I can locate the actuator and other parts you mentioned.
Thanks for your patience with the newbie! When you find the actuator, you will see the 2 hoses one on each side of the diaphram. With the truck running pull off the hoses one at a time and see if its sucking air. Do it in 2wd then in 4wd. One should suck air in 2wd and the other should do it in 4wd. I will check mine when I get home to make sure which one is which.
Maybe somebody hooked them up backwards. Thanks for the clarification! I am a member of 4x4wire forums and I couldn't get any help on this topic at all. I really appreciate you taking the time to answer my questions! If you're ever in the Bay Area, I'll happily buy you a few beers! Thanks again! Here is a pic of the actuator with the vacuum lines identified.
The actuator is on the front of the axle housing on the drivers side. I tested both vacuum lines and found that I couldn't feel either with my fingertip.
I ended up taking a small piece of paper and holding it near the hose. The 4WD line had a little bit of suction barely enough to hold the paper , and the 2WD had none.
What does that mean? I assume you tested both lines in 2wd and in 4wd? Either way the problem seems to be down to the vacuum switching solenoids or the vacuum line supplying them. There should definatly be enough vacuum to feel it with your finger. I will try to trace the hoses back from there and see if they are disconnected. I am guessing that since the light started blinking immediately after the lift was done that it could be a very simple fix like the hoses being unplugged or something.
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