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Isuzu Trooper TOD and 4WD Problems

I was wondering if anyone else is having issues with their Torque on Demand systems going into 4WD. The 4WD does not engage at all and the TOD display on my dash blinks at me for about 60 seconds and then the red "CHECK" light starts flashing at me. I know nothing about the TOD system and the 4WD does not engage into 4LOW when I do it manually either...any ideas?
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Comments

  • atfdmikeatfdmike Posts: 414
    No such animal.....LOL
    Are you referring to the actuator inside the T case, or one of the sensors on the outside of the T case, etc.
    Any way, best new parts source I know of is Jerry at jlemond@bellsouth.net. A dealer with free shipping and good prices online is St. Charles Isuzu. Ask for Merlin there, although any parts guy will help you. They ship from the distributor and it is fast. I have used both. I think you will have a tough time finding new at better prices, and used are tough unless you live near a parts yard, etc.
    Good luck.
  • I am a new trooper owner with a 2001 that I can not get the TOD to engage. The auto light continues to flash but the front wheels never engage. Can you put manual hubs in this?
  • paisanpaisan Posts: 21,181
    It is likely your front actuator for the 4wd. I had this problem happen on 2 troopers, one time it was locked in AWD/4wd mode after not engaging/disengaging for 2 months, the other time it wouldn't engage due to not being engaged for 2 or 3 months.

    -mike
    Motorsports and Modifications Host
  • It looks like this seems to be an issue with mine as well...how much did this cost to fix? My wife is hounding me to get it done because of all the snow we have been getting this winter. :P
  • costello1costello1 Posts: 60
    Just had my 02 Trooper in and the TOD light was blinking. $1342 to replace speed sensor A and B plus a new solenoid . Not many Izusu people left in my area so I don't have many choices .I want someone who knows what they are doing!!! I will have 100k on it in a few weeks. This is my third Trooper , I had a 86 and 88 . Is this the going rate , I use the unit for surf fishing and driving on to the beach .I also have to replace the rear brakes and rotors for 379.00 and Rt frnt axle and axle seal for 469.00. There goes my tax rebate !!!! Thanks GW !!!
  • wesbellmorewesbellmore Posts: 11
    Mike (paisan)

    2001 Trooper, bought new, 60,000 miles. Always maintained.

    Where exactly is the actuator for the 4wd? My 2001 Trooper will not go into 4wd, but I can hear the mechanism "trying" to engage when I push the dash button. (Light flashes, does not go on full-time.)

    At city speed, if I press the dash 4WD button I can hear a slight "cli-click" from front axle area. SOMETHING seems to engage slightly, because I can hear a very slight whine and the engine feels like its under a tiny bit extra load, but the 4WD light on the dash never goes on full, it just blinks. Then, when I hit the dash switch again to "disengage" , I hear a slightly different sounding "click clunk" and the dash 4WD indicator stops flashing and goes out.

    Is this a vacuum actuator issue, or could it be the little "fork" just inside the end of the axle that engages the front axle is not sliding properly?

    If you can point me to any good repair instructions, that would be great!

    Wes
  • tdostertdoster Posts: 1
    Actuator is on the front axle. This is NOT your problem. Problem is more than likely the speed sensors on the transfer case. These send signals back to the computer to indicate slipage in either the front or the rear to engage or disengage the clutch in the front. These things are a pain in the rear, and very expensive. They are no different from speed sensors on many cars, and cost more than the sensors on my last Porsche. If you have a dealer fix, they will usually only replace them both at a cost between 1,100 to 1,500 and going up every day since it is so hard to get at them. Meaning one could and probably is good. Bad way to spend $350 for a part in my opinion. They also have to reset the codes, which you have to have the special software to do as well, so this is not a weekend mechanics job, and easy to mess things up. BUT, there are so many things that can go wrong, it is impossible to diagnose yourself, and even the dealers that are left are taking the code and replacing all sensors instead of the one that is out. All of the good Isuzu mechanics are working for other dealers now which have more cars coming through.

    When you press 4 wheel on the dash, a solinoid is sent a signal that changes the vac preasure at the front axle, which locks the front wheels to the shaft. It then puts the computer in motion to look at signals from the various sensors to apply the clutch in the transfer case to add power to the front wheels when they begin to spin. It uses a speed sensor at the output shaft of each side to indicate what is happening. If one of those sensors goes out, then the computer can't calculate when to engage the clutch and will begin by the TOD not starting at all. It is possible that the computer got confused and needs to be rebooted by clearing the code, or removing the battery cable for 30 min. If the system does not work still, it will eventually go into check mode and they system will stop functioning all together. This is also the case when some people have it get stuck in locked mode, then turn it off. Signals are wrong to the computer, so it quits. Same with the clutch. But most of the time, it seems that the speed sensors on the output shafts are the failure point, which is hard to believe somthing so solid state would go out. Bad design, just as the piston rings, but that is another story.

    I wanted 4 wheel, but TOD was just cutsy to engage when there is a little snow or ice on the ground and you want the front wheels to kick only when the back start to spin. So, you decide if you want to pay over a grand for cutsy or just bypass the computer and engage it when you want 4 high. Just have to be careful on dry roads with it.

    Google an article on planetisuzu for converting to lock 4 wheel. When my sensors went out, I bypassed the system to lock the clutch in when I put it in 4 wheel drive. Loved the TOD, but for a weekend and $20 in parts, I am happy to have 4 high with it locked in as opposed to $1300 and it could go again by bad design.
  • Regarding the comment above, "They also have to reset the codes, which you have to have the special software to do. " As an FYI, you do not need special sofware to reset the TOD ECU DTCs (Diagnostic Trouble Codes). To reset the codes, all you have to do is ground the #8 pin on the diagnostic link connector, located just to the left and slightly below the steering wheel (on my 2000 Trooper) under the pop-open cover, and then follow a few simple reset steps. First, take about a 1 foot length of small gauge twisted wire, form a small point and insert in the #8 pin and hold or connect the other end to a ground point, which includes the metal back plate and/or bolt/nut under the diagnostic link cover. The #8 pin is the lower left pin. For orientation, the lower right is #1, lower left is #8, top right is #9, and top left is #16. This appears upside down in many manuals, so how can you check to ensure you have the #8 pin? Simple... with the pin grounded, turn the ignition swithc to ON (don't have to crank). The flashing check light will now appear as the DTC indicator, which begins by flashing the normal operation (DTC 12). If you are shorting the #8 pin, you will see one flash of the "check" light, followed by two successive flashes (1 and 2 equals code 12). It will do this 3 times. If you want to see what other codes are in memory, continue to keep the #8 pin grounded. After the 3 "normal" DTC codes, it will then display the next DTC code. If you see one flash, followed by 3 successive flashes (Code 13), it indicates a circuit is shorted to ground. A summary of all 2000-2002 Trooper codes is shown below:
    12 - Normal Operation
    13 - Reference Circuit Shorted To Ground
    14 - Front Speed Sensor Open Or Shorted
    15 - Reference Circuit Shorted To Power
    16 - Front Speed Sensor Has No Running Speed Puls
    21 - TP Sensor Has Faulty Voltage, Shorted Or Open
    23 - ECU Failure
    24 - Rear Speed Sensor Open Or Shorted
    26 - Electromagnetic Coil Shorted To Ground
    27 - Front Or Rear Speed Sensor Has No Pulse
    28 - Axle Disconnect Output & Axle Switch Output Abnormal
    31 - Electromagnetic Coil Disconnected Or Shorted
    32 - Axle Disconnect Output Shorted Or Disconnected
    33 - Axle Disconnect Output Circuit Shorted To Ground
    36, 37, 38 - ECU Failure
    So, now that you have read the code, let's get back to resetting the TOD ECU. Begin by turning the ignition back off, then shift the 4WD Transfer Lever (HI to LOW selector beside the auto tranny stick) to the neutral position. Ground terminal #8 again of the diagnostic link connector. Turn the ignition back ON and depress the brake pedal 5 times WITHIN 5 seconds. The TOD indicator will display the 4L indication (all front and rear indicators are illuminated) each time the brake pedal is pushed. If you don't see this happen, then you are not properly grounding the #8 pin connector or are not in the neutral position with the 4WD HI/LOW selector. When properly performed, this will reset the TOD ECU. A confirmation is provided by displaying only the normal check (DCT 12) indication. So, based on the codes above, this is not completely "impossible to diagnose yourself" as stated in the earlier post. In my opinion, the front and rear speed sensors probably should be changed at the same time since they are wired together inside the same terminal connector block (M-27) which is located on top of the transfer case and a real pain to get to. Note that if only one or both of your speed sensors are bad, you will always have 4WD LOW range, which bypasses the TOD ECU slippage/speed calcs, and transfers 50/50 torque between front and rear wheels.

    When this happened to me (flashing check light), I verified all of the above, confirmed I had full time 4-wheel low (when transfer case in LOW speed), and verified I had minimal clutch output to the front axles (with TOD in 4WD AUTO). With the faulty speed sensor, I could not get full torque in HI, but a little extra pull was better than nothing at all.

    By the way, disconnecting the battery for 30 minutes does nothing to reset the TOD ECU but will reset the actual engine computer (ECU or ECM in some references, plus loses all of your radio stations... LOL).
  • This is my first visit back to the forum since posting...I forgot to turn on the email reminder to let me know there was mail.

    THANK YOU for your detailed message! It makes me a bit peeved at Little Mr. Isuzu and his weak mechanisms... anyhow.

    Do ALL Trooper 4x4 have Torque on Demand? I was reading about it in the manual, and although I have shift on the fly 4x4 (dash switch) I don't think mine is equipped with TOD. Would this eliminate the issue of speed sensors if I do NOT have TOD?

    Wes
  • my TOD still does not engage properly it will flash but if I leave it on after shutting off the car and parking it. I can then start the car in the morning and it will engage. ANY IDEAS?
  • I believe 98 and earlier were standard 4x4 (push button with full engage) with TOD becoming the standard in '99. There may have been a few in '99's without TOD. I have owned 98, 99, and 2000 but only my 98 was NOT TOD. If there is no TOD, I believe there is no need to have the speed sensors since the full amount of torque is being applied at all times but I am not 100% sure because my 98 never gave a moments trouble (was totaled in a rollover in 99 with less than 30,000 miles). The TOD indicator is visible on the left-side of the insrument cluster and displays a progressive indication of torque application, using 3 bars. At low torque transfer to the front wheels, only the first bar is illuminated; more torque transfer results in additional bars being illuminated. If you do not have these, you do not have TOD.
  • Thanks 'hiprollc'... OK, good news for me... my '01 Trooper does NOT seem to have TOD by your description... I have NO progressive bars on the dash, just that little 4x4 icon that lights up when 4x4 is fully engaged or, in my case, mockingly flashes at me when I press the dash switch and says "ha ha, I'm not going into four wheel drive for YOU, buddy!"

    At idle I can hear a 'ca-clunk' when I press the dash switch for 4x4...the icon blinks but it does NOT engage. If I engage the 4x4 switch in the morning after the vehicle has been sitting all night, the 4x4 MIGHT engage and operate normally. Now and then I can get it to engage when I press the 4x4 switch with the engine OFF and then starting it. When the front axle DOES decide to engage, it runs fine...no strange noises, no clunks, so I feel pretty sure it's ENGAGEMENT system is not working right...

    ANY THOUGHTS???
  • i have a 1999 trooper.can anyone tell me what pin connector to short so i can read my tod codes.after reading is there a way to clear the codes?thanks
  • after reading all these forums i shorted the #8 connector on my 1999 trooper and got six codes.12,14,24,28,31,32.i them tried to clear them as stated here.every time i pushed the brake pedal the front indicators lighted as stated the rears never did.afterwards the check light blinked all 6 codes agian.what does this mean?thanks for any ideas.these forums are great.finally making slight progress
  • one more question.with all these codes i have i can see where my 4 high(tod)might not work but why isnt my 4 low working anymore?it goes into 4 low but doesnt lock the front wheels.thanks agian.
  • Sorry about the slow and late responses, just don't spend much time on the computer anymore. Brentb1... with all those codes, my guess is that someone probably already has "diagnosed" problems with the 4WD system and probably disconnected some of the sensors in order to try to eliminate the codes, but probably just made it worse. Did you buy this vehicle new and these issues just start or did you buy it used and it was like this when you bought it? f the 4-low is not working, that means the vacuum solenoids are not engaging; could be electrical or vacuum related and is common for vehicles that are normally run on the highway and never "cycled" into 4WD. With all your codes, I wouldn't know where to begin. By the way, once you reset the codes and then restart the vehicle or even go back to the ON position, the sensors will immediately return all the codes unless you have corrected the problem. So, when you get an item fixed, you can reset the TOD ECU and that code should not reappear; if you don't fix it, the code immediately returns.
  • not sure what all the codes mean that i have but i did find the front 2 vacuum soleniods to be bad.1 is stuck open and the other is stucked closed.si what i did for now was switched the vac.lines around so the one that has vacuum will lock my axle actuator and it worked.i have low and hi now.dealer here wants 200.00 for the soleniods(crazy).what and where is the electromagnetic coil?that is one of my codes and what does it do?thanks for everyones help.
  • chappechappe Posts: 2
    I was just seaching for a place to post this same exact thing!!! I am so frustrated!!! We haven't had snow all winter, finally when we get it, I can't get back up the hill as I have no 4WE. That light on the TOD display flashes red . I read in the owners manual that we should not drive the car in this situation. I drive a 1998 model. Anybody else? Thanks!
  • I had same issue and took to a trans shop. Started to talk to the guy and we became friends. He told me that the tod works with vaccum, and it unplugs, you can look at the front diff, there is a plate that cover a vacuum diaphrame and one of the hoses may be disconnected. That's what happened to my trooper.
  • Can anyone tell me if their is a difference in the 3.5l regular and the 3.5l performnace. I'm having fuel economy problems and don't know where to begin. the other thing is seams to have a small cap fuel tank. every time i fill up it only goes up to 18 to 19 gallon
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