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SUVs Isuzu Trooper Isuzu Trooper TOD and 4WD Problems
45 messages, Last post on Nov 22, 2009 at 9:47 AM
You are in the Isuzu Trooper Forum. Your Hosts are steve_ & tidester
| 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? | |
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Replying to: dweave3 (Feb 06, 2008 1:00 pm) -mike Motorsports and Modifications Host
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Replying to: paisan (Feb 06, 2008 4:55 pm) 
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Replying to: boottmills (Mar 08, 2008 5:44 am) |
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Replying to: paisan (Feb 06, 2008 4:55 pm) 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
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Replying to: wesbellmore (May 21, 2008 3:40 pm) 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.
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Replying to: tdoster (Jun 23, 2008 7:09 am) 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). |
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Replying to: tdoster (Jun 23, 2008 7:09 am) 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
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Replying to: dweave3 (Feb 06, 2008 1:00 pm) |
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