Speedometer calibration questions - again.

[Doc2012]

Ok. So no way to fix this except 3rd party speed boxes? Hmm. I need to investigate this further. As the 4 runners came with both 15 and 16 inch rims. Something has to be telling the speedometer the wheel speed. I always thought it was the rear abs sensors. Or in non abs the transmission vss sensor.


On the vss sensors. The diff ratio would matter.

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Correct.

Because no one has successfully gotten into the 3rd Gen 4Runner ECU.


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[Doc2012]

How do I PM you? I don't see a private message link that I can click.

I sent you a PM.


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[phattyduck]

But.....if my math is correct, an ABS module for a 4.30 geared 4Runner with 265/70/16 tires will produce a speedometer signal that is within 1% of accurate when used in a 3.91 geared 4Runner with 265/70/16 tires that was originally equipped with 225/75/15 tires.

Gear ratio has nothing to do with the speedometer on ABS equipped 3rd gen 4Runners. Since the ABS tone rings are used, only the speed that the hub is rotating matters (not the trans/t-case output). I ran a 4.10 rear gear for a bit with the small tires - it was fun!

I have a Dakota Digital SGI-5E on mine too. It has a glitch right around 55mph - so can't use cruise there... but otherwise it works fine. Trans shifting, etc. is handled separately from the speedo. Went from the 15" wheel size to 265/70-17's with (I think) a 12% adjustment.

-Charlie

 

[95Z28A4]

I sent you a PM.


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Got it. I'll follow up today. Thanks.

 

[95Z28A4]

The ABS module does not care what differential gearing you have as that is before the wheel speed sensors. Any changes/differences after the wheel speed sensors (tire size) is what the ABS module has to calculate for.

Gear ratio has nothing to do with the speedometer on ABS equipped 3rd gen 4Runners. Since the ABS tone rings are used, only the speed that the hub is rotating matters (not the trans/t-case output).
-Charlie

OK....I get it now. Because the tone rings are mounted on the axles, they turn at the same RPM as the wheels regardless of gear ratio.

Shouldn't any ABS module for a 1997 non-locked 3.4L 4Runner with 16" wheels correct the speedometer?

 

[95Z28A4]

I found these ABS modules listed on the ToyotaPArtsDeal website. Many are available used through car-part.com. How do I determine which of the vehicle options I have? Is there an option code label somewhere in the vehicle? Similar to the RPO code label GM affixes to the inside of the glove box? Please excuse my ignorance. I have been wrenching on mostly US vehicles for the last 45+ years.

Thanks.

 

[Bad Luck]

OK....I get it now. Because the tone rings are mounted on the axles, they turn at the same RPM as the wheels regardless of gear ratio.

Shouldn't any ABS module for a 1997 non-locked 3.4L 4Runner with 16" wheels correct the speedometer?

In theory yes since you are going to a stock size, but that would be a trial and error sort of situation as no one can verify what each of the module options available do exactly. They may be for the correct size, but what are the other differences between them that require a different part number? It could be anything from different caliper size calibrations to different manufacturers for the same part.

EDIT: I know you keep saying wheel, but to clarify it's the overall tire size that is important for the speedometer calculation not just the wheel size. I'm pretty sure we're saying the same thing here, but wanted to make sure.

 

[brillo_76]

I would think it would be the tone ring or the abs ecu that are different between the 15" vs the 16"

The sensors would be the same. The conciseness is its best to goto an aftermarket speed module to correct this problem.

I can understand 17 " wheels or larger would need aftermarket speed module to correct the difference as the 3rd gens never came with those wheels.

I just really find it odd that being these rigs came with both 15 and 16 wheels from the factory that things cant be switched to correct the speedometer. Could be the case, just extremely odd.

 

[95Z28A4]

In theory yes since you are going to a stock size, but that would be a trial and error sort of situation as no one can verify what each of the module options available do exactly. They may be for the correct size, but what are the other differences between them that require a different part number? It could be anything from different caliper size calibrations to different manufacturers for the same part.

EDIT: I know you keep saying wheel, but to clarify it's the overall tire size that is important for the speedometer calculation not just the wheel size. I'm pretty sure we're saying the same thing here, but wanted to make sure.

Thank you for the clarification. I am aware of the difference between tire and wheel size. I have been using 15"/16" wheel because it's easier to type than 225/75/15 (28.29") or 265/70/16 (30.61").

 

[95Z28A4]

I decided to roll the dice. I purchased a used ABS module part number 89540-35111. I paid $31.58 shipped. A new one sells for $371.09.

I copied the description below from toyotapartsdeal.com.

Computer Assy, Skid Control
W(265/70R16 SIZE TIRE)
Production Date:
08/1996-08/1997
Fitting Vehicle Options:
VZN185.. SR5V; VZN185.

It should arrive early next week. I will report back with the results.

 

[brillo_76]

Good deal. I am expecting it will correct your issue. As it has to be the module ecu that controls the speed signal. I am hoping for the best outcome.

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[Doc2012]

Good deal. I am expecting it will correct your issue. As it has to be the module ecu that controls the speed signal. I am hoping for the best outcome.

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From my understanding the ABS Signal goes into the ECU then into the cluster.

ABS systems don’t have a ‘ECU’ in them on the 96-00 trucks like the 01-02.

Therefore; the ECU, from my understanding, is what controls the Speedo.

Which is again, why, the Speedo can not be corrected without an outside influence; because no one has successfully cracked the 3rd gen 4Runner ECU coding.


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[brillo_76]

From my understanding the ABS Signal goes into the ECU then into the cluster.

ABS systems don’t have a ‘ECU’ in them on the 96-00 trucks like the 01-02.

Therefore; the ECU, from my understanding, is what controls the Speedo.

Which is again, why, the Speedo can not be corrected without an outside influence; because no one has successfully cracked the 3rd gen 4Runner ECU coding.


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So your thinking it's the main ECU? I wouldn't think they make all these different versions of abs with mentioning 16 inch tires unless the circuitry would be in it.

I need to pull my kick plates off and compare the abs units as I have a 1998 with 16 wheels and a 1998 with 15 wheels both with abs. I expect them to be different part numbers.






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[Doc2012]

So your thinking it's the main ECU? I wouldn't think they make all these different versions of abs with mentioning 16 inch tires unless the circuitry would be in it.

I need to pull my kick plates off and compare the abs units as I have a 1998 with 16 wheels and a 1998 with 15 wheels both with abs. I expect them to be different part numbers.






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Different manufactures made the ABS units; ford and Denso.

I honestly do t think they have anything to do with fixing a Speedo.

It’s all in the ECU.


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[brillo_76]

Different manufactures made the ABS units; ford and Denso.

I honestly do t think they have anything to do with fixing a Speedo.

It’s all in the ECU.


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Could be. Most of mine say asin mfg on the ones I have seen. I am hoping there is another way to correct with 3rd party speed control s.

If it's an abs electrical control unit or the main Electrical Control Unit. So be it. Being I have many of these, 3rd gens it makes sense that I run the 16 inch rims. As all my other ones run 16 inch rims.

I don't blame the OP for trying things as that is how things are learned and figured out. That's his call.

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[Bad Luck]

According to my 2000 EWD the instrument cluster (combination meter) gets the speed signal from the ABS ECU for 5VZ or the vehicle speed sensor for 3RZ.

 

[RandyBobandy]

According to my 2000 EWD the instrument cluster (combination meter) gets the speed signal from the ABS ECU for 5VZ or the vehicle speed sensor for 3RZ.

This is correct, the signal goes from the wheel speed sensor to the abs ecu then to the speedometer and finally to the main ecu. You can run around with the speedometer completely disconnected from the main ecu and still have a functioning speedometer

 

[phattyduck]

This is correct, the signal goes from the wheel speed sensor to the abs ecu then to the speedometer and finally to the main ecu. You can run around with the speedometer completely disconnected from the main ecu and still have a functioning speedometer

I can confirm this too - ABS computer -> Cluster -> Engine ECU (for ABS 4Runners)

I too would suspect the ABS computer is where the factory adjusts the speedometer signal for different tire sizes.

-Charlie

 

[brillo_76]

Here are 6 of my 7 3rd gen. The only one missing is an 01 sport and we know that's a totally different abs system in 01 and 02. These are all v6 4x4 with the year and trim labeled. I am curious if the op abs module is blue too.

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[95Z28A4]

Here are 6 of my 7 3rd gen. The only one missing is an 01 sport and we know that's a totally different abs system in 01 and 02. These are all v6 4x4 with the year and trim labeled. I am curious if the op abs module is blue too.

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You are correct my module is blue. The part number is 89540-35101. Notice it has a cover that snaps on. Your 89540-35102 from a 1998 has a screw on cover.

I have made a few observations.

• 89540-3509x modules have the same color label (GREEN) and are for 2WD 4Runners with 15" wheels (225/75/15 tires).

• 89540-3510x modules have the same color label (BLUE) and are for 4WD 4Runners with 15" wheels (225/75/15 tires).

• 89540-3511x modules have the same color label (RED) and are for 4WD 4Runners with 16" wheels (265/70/16 tires).

• 89540-3512x modules have the same color label (BROWN) and are for 4WD 4Runners with rear lockers.

• 89540-3513x modules have the same color label (ORANGE) and are for 2WD 4Runners with 16" wheels. (265/70/16 tires)

Also, it seems the ABS modules went from snap on covers to screw on covers in 1998. It's interesting that the modules with screw on covers are no longer available, but the modules with snap on covers are still available.

Everyone feel free to list examples that disprove my observations. I'm not touting this information as fact, but only as my personal observations.

Edit: I added two additional photos so this post will have at least one example of each type of module.

I realized the 4 character alpa/numeric code on the label or on the wire socket is actually a date code. This code agrees with the model year of that 4Runner. The first character is the year. The second character (letter) is the month. The last two digits are the day of the month.