Last post on Oct 10, 2013 at 6:43 PM
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Isuzu Trooper, Transmission, SUV
#22 of 60 Re: 2001 TOD auto flashes but does not engage [tdoster]
Sep 01, 2008 (8:09 am)
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).
#23 of 60 Re: 2001 TOD auto flashes but does not engage [tdoster]
Oct 27, 2008 (4:05 pm)
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?
#24 of 60 Re: 2001 TOD auto flashes but does not engage [dweave3]
Oct 27, 2008 (4:45 pm)
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?
#25 of 60 Re: 2001 TOD auto flashes but does not engage [wesbellmore]
Oct 28, 2008 (3:24 am)
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.
#26 of 60 Re: 2001 TOD auto flashes but does not engage [hiprollc]
Nov 08, 2008 (6:49 pm)
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...
#27 of 60 Re: 2001 TOD auto flashes but does not engage [hiprollc]
Nov 18, 2008 (3:31 pm)
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
#28 of 60 Re: 2001 TOD auto flashes but does not engage [hiprollc]
Nov 19, 2008 (4:07 pm)
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
#29 of 60 Re: 2001 TOD auto flashes but does not engage [hiprollc]
Nov 19, 2008 (4:27 pm)
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.
#30 of 60 Re: 2001 TOD auto flashes but does not engage [brentb1]
Nov 20, 2008 (4:14 pm)
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.
#31 of 60 Re: 2001 TOD auto flashes but does not engage [hiprollc]
Nov 23, 2008 (2:04 pm)
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.