Blinking 4x4 dash light

Can anyone tell me what a constant blinking 4x4 dash lcon light means? This happens when I hit the 4x4 button, usealy the light goes on solid but now it just blinks untill I unselect the 4x4 option. It is going into 4 wheel drive because I can feel the heavy steering so I beleive the selection mech. is working. I have tried the owners manuals fix for this issue with no change. All tires are the same size and in good shape. 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 think you may be on to something with that vacume / computer sensor idea. 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. If I put the truck in 4WD, the light goes solid, and I can clearly feel it go into 4X4 (both 4H and 4L), but while in 2WD, the light still flashes. 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). The stealership wants $180 just to look at it, any other ideas that might not be so painful to my pocketbook?

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.

Sorry about that, I have a 1999 Rodeo LS 4X4. Its a 5spd. I hope you're wrong about the truck not coming out of 4WD, I've probably put on about 4-5k miles since its been doing that.:disappoin

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. Short of seeing a vacuum hose not attached, how can I tell if the 2WD and 4WD vacuums are working? Thanks for your patience with the newbie!

Short of seeing a vacuum hose not attached, how can I tell if the 2WD and 4WD vacuums are working?

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!

Anyway, I checked and I cannot shift from 4H to 4L while in 2WD, it doesn't even budge. If I can locate the actuator before I get the repair manual, I will check it ASAP and get back to you. 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.

http://i30.photobucket.com/albums/c337/Gizmo420/Img_0469.jpg

The vacuum is very slight so you will have to put your finger on the end to tell if it has vacuum or not.

Thank you sooooo much bro!

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 did try them in both 4WD and 2WD, I only felt the 4WD vacuum line when I had the truck in 4WD. 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). Is that logical? Do those hoses connect near the firewall or somewhere else?

Just in case that's not it, where can I order the vacuum solenoid? I searched Autozone and didn't find anything.

I think the solenoids or on the firewall by the brake booster. They might have unplugged it, pulled a vacuum hose loose, pinched one, or could be coincidence. The VSS isnt very cheap, $116 from the dealer you could probably get one a bit cheaper from St. Charles Isuzu or pm UNDERDOG on planetisuzoo.com he works for dealer and gives discounts. I have seen one post before where someone found the 4way vacuum line splitter (its in the same area) broken. That would have to probably be a salvage yard item, I dont think its available from the dealer.

The problem could also be the computer not telling the solenoids to switch but I would think you would have good vacuum on one of the lines then.

so I think I traced the vacuum lines back correctly... these are the two vacuum lines and are not connected to anything. Did I trace them back right?
http://i204.photobucket.com/albums/bb299/tnobori1/IMG_0561.jpg

Unless someone switched hoses around then no. Those would be breather tubes. One is for the front diff, dont know what the other one is for. The vacuum switching valves are directly above that though. They are actually held there by the 4 way block I told you about that someone found broken on theirs. Check it to make sure its ok, then check for vacuum on the line going into it. If its ok then the problem is in the valves, you can recheck for vacuum in 2wd and 4wd right at the valve and see if you loose vacuum there (looks like the one with the blue plug is 2wd and grey plug is 4wd). If you dont have vacuum going into the 4 way block then start following it back to the intake manifold checking for vacuum till you find the problem part. You should also check for vacuum on the vacuum tank wich is right above the axle actuator, if that line came loose you could be losing vacuum to everything. I forgot about it.

Here is a diagram to help you with tracing things out..
http://i30.photobucket.com/albums/c337/Gizmo420/vsvpiping.jpg

Okay, I think I may have found it. I can't believe I missed it before, but when I had the truck on I could hear a loud sucking sound inside the engine bay. I had seen this hose unattached before, but assumed it was nothing. I put my finger on it and got a lot of vacuum from it. Where does it go and how do I connect it? Is it supposed to go to the inlet manifold? What does that look like?

http://i204.photobucket.com/albums/bb299/tnobori1/IMG_0564.jpg

http://i204.photobucket.com/albums/bb299/tnobori1/editvac2.jpg

http://i204.photobucket.com/albums/bb299/tnobori1/editvac1.jpg

That open line should plug into the end of the solenoid with the red plug.

http://i30.photobucket.com/albums/c337/Gizmo420/IMG_0470.jpg

I dont know what that solenoid is for. Could definatly be a problem with the 4wd system not getting enough vacuum though.

Thanks so much Gizmo! That was the problem. The stupid thing wasn't plugged in... what kind of a shop misses that detail? The worst part is that the guy went out of business (I wonder why) and my lifetime warranty means jack s#%t now. The blinking stopped, and my truck is running better now too! Thanks for all of your help. I work for Auto Trader, so if you ever need an ad run, I will happily do it for free. I know that's not much, let me know if there's anything I can do.

Tak

Not a problem. Glad I could help and got it solved.

jimbar
Any progress on yours?

Havent used 4 wheel drive lately so I havent messed with it..but now it looks like im going to give it a shot. I'll let ya know how it turns out.

yep, just got a call from the repair shop.... I've got a bad actuator.... CRAP! And I was hoping to take it to the beach next weekend.

Edit:
Dealership wants $530 for a new one..... Anyone want to buy a '98 2WD V6 Rodeo?

Dealership wants $530 for a new one.

:eek2::wtf:

Is that just for the part or installed? www.slhondaparts.com lists it for $176 for a new one.

Any chance somebody can talk me through this problem with a 01 honda passport? where do i find the actuator to start my problem solving?

The actuator in on the front axle, left side and has two vacuum lines and a wired plug attached.

New to the forum. Sorry for resurrecting an older thread, but this seems to be the thread everyone points to.

My son has a 1998 Isuzu Rodeo 4x4 Automatic. When he first bought it the 4x4 did work fine, so hopefully nothing fundamentially wrong. After pressing in the 4WD button the light on the dash just blinks at a constant rate. I'm guessing 2Hz blink rate. Pressing it again will stop the blinking. I have driven the vehicle for some distance with it depressed and no change.

Vacuum is always present on the 2WD vaccum line and never on the 4WD vacuum line. I traced back to the VSVs and the same things applies there, regardless of switch position. I replaced the V$Vs with brand new parts and have the same symptom.

Next I checked voltages on the C31 and C32 connections to the VSVs and there is a constant 12+ volts on the 2WD blue VSV and 0 volts on the 4WD gray VSV connection, no matter if the switch inside is pressed in or not.

My next suspicion is with the 4WD (or $WD) Control Unit mounted underneath the console. I have not gotten into that yet. Am I on the right track here? I've got the Service Manual and from what I can tell the voltage for the VSVs comes from the 4WD Control Unit. Let me know your thoughts. I'm hoping it is not the ECU that is faulty. His check engine light is not on and there are no fault codes found when I hooked up to the OBDC connector.

Is the 4WD Control Unit available new or would I be looking at a junkyard for a possible replacement? If new, anyone know the part number and approximate price for this unit?

Thanks
Chad

I had a little time this morning to work on the problem before my son needed the Rodeo to go to work. I took out the passengers seat (4 - 14MM bolts with rear two under the covers) and removed the rear console portion (two phillips screws in console pocket). Pulled up and forward on the console and got to the Part number 8971659580 "little black box". Actually, they call it a "TRANSFER CONTROL UNIT", which is the 4WD Control Unit in the manual. Two phillps screws hold it to the floor underneath the emergency brake handle. I'm still convinced this provides the power changeover for the Vacuum Switching Valves. I ordered the part from IsuzuParts.com for $78.57 with tax and shipping. Should get it sometime next week.

A couple of pictures for reference.

38214
38215

I've got the same pronlem on my 98. Its a 4wd manual and i was wondering is there a certain way to take the rubber tubbing off without tearing it. I really don't want to have that happen.

I've got a 99 Rodeo LS, automatic 4WD and I'm having the same problem with a blinking 4WD indicator. I've checked the actuator and it's fine but I noticed the vaccum solenoid on the firewall that works with the actuator is making a "psssssh" sound like it's leaking vaccum. I wonder if this could very well be the cause of my blinking 4WD indicator light?

Sounds like you already found your problem. Take a close look at the vacuum lines first though. There could be a small, unnoticeable leak in one of them.

I've got a 99 Rodeo LS, automatic 4WD and I'm having the same problem with a blinking 4WD indicator. I've checked the actuator and it's fine but I noticed the vaccum solenoid on the firewall that works with the actuator is making a "psssssh" sound like it's leaking vaccum. I wonder if this could very well be the cause of my blinking 4WD indicator light?

Yeah, I would just replace the vacuum lines and see if that fixes it. You may need to reset the ECU, but I don't think I did. Good luck and keep us posted!

I got the solenoid but can't figure out how to get it off the brakcet to replace it. Any suggestions/ideas?

Well....nevermind. I replaced the solenoid on the firewall and nothing. I'm about at my wits end. None of this started happening until I had the front drive axles replaced along with the ball joints and the front shocks.

Hi, I have gotten my 4x4 to work finally, replaced the valves, BUT, it engages, and I have a steady light, but now, it blinks in 2 wheel drive. Works fine other than the blinking. What do I check next, I did not see anyone with similar problems.

Thanx guys

Jon

I had a little time this morning to work on the problem before my son needed the Rodeo to go to work. I took out the passengers seat (4 - 14MM bolts with rear two under the covers) and removed the rear console portion (two phillips screws in console pocket). Pulled up and forward on the console and got to the Part number 8971659580 "little black box". Actually, they call it a "TRANSFER CONTROL UNIT", which is the 4WD Control Unit in the manual. Two phillps screws hold it to the floor underneath the emergency brake handle. I'm still convinced this provides the power changeover for the Vacuum Switching Valves. I ordered the part from IsuzuParts.com for $78.57 with tax and shipping. Should get it sometime next week.

A couple of pictures for reference.

38214
38215

Be careful on this one. I had my '03 diagnosed as needing the 4x4 control module replaced. So I bought one. The exact same part number as the one you have in the pictures here. I get it from a junk yard, and over the summer keep putting off replacing it. After all...no real need for 4x4 during the summer. I go to swap out the unit last week during a snow storm and find out that this unit also controls the ABS on Rodeo's that are equipped with ABS. Long story short....I have the wrong part and since I waited so long, I can't get a refund.

On a side note, does anyone have a good link to a used parts source? I need to fix this ASAP. My wife is pregnant. She is due Friday, which means the baby could come any day now, and snow is in the forecast. I know....this is what I get for procrastinating.

I'm having trouble with the 4 wheel drive on my 97 Rodeo. I can engage it and it will work for a minute or so and then disengages.
The llight comes on ititially and then goes off when it disengages.
From reading this thread I think I have a leak in a vacuum hose. I theorized the leak is small enough where it will engage but then leak down and disengage.
I'm not sure though if the system keeps a vacuum on the 2 wheel side while the 4 wheel is engaged. If it does then as soon as the 4 side leaked down the 2 side would pull it back. If not there may be enough tension in the diaphragm to pull it back when the 4 side loses vacuum. Either way the 2 side VSV would pull it back when I shift back to 2 wheel drive.
Does that sound right?
Thanks

Old thread here but if anyone reading, my 4wd link is on not blinking. I change the dial from 2 to 4h or 4l and nothing happens.

i popped the dial out and tested the wires with the car on and there is no juice in any of the wires.

I tried to trace it but can not see where it leads to, anyone have a wiring digram or where the wire goes?