I will be updating with pics soon.

1st gen 4runner/ 2nd gen pickup / clusters with mechanical speedo / Automatics- A340H/A340E/A340F
This is all i have learned about these darn things.


1988 Cluster w/auto lights + tach




1986 cluster, auto lights -tach




Automatic trans speed sensors, if you have a cable driven speedo, There are 2 sensors.

Speed sensor #2 is on the drivers side of the transfer case with 2 wires. Just above shift linkage. You test it buy jacking up one wheel, spinning drive line and checking for (continuity >< no continuity) back and fourth.



Speed sensor #1 is in the cluster, and supposedly uses Reed switches. No idea how to test it, is there a way? Is there any adjustment? #Check post 4, from scope103!

Now, from what i have read the electronic transmission controller or ECT, reads both of these signals, and when they dont compare to each other (I.E one sensor fails) it runs off the other one. Now i also read that if a discrepancy is sensed, it switches to the #1 speed sensor in the dash. (correct me if I learned incorrectly)

Check this link for how the Electronic transmission works
http://www.autoshop101.com/forms/h16.pdf

Here are some pics pulled about speed sensor















Now if you have a cluster with electronic speedometer. (The top cluster in this picture)





You still have 2 speed sensors.

#2 Speed sensor is the exact same as above. Up untill 1995 that know of.



#1 Speed sensor goes in the rear of the transfer case next to the rear driveshaft.





SO..... I recently did a cluster swap on a 1986 4runner with a 22RE + A340H automatic trans. Got a gauge set out of a 88 4runner with the 3.0 V6 and A340H trans.
All went well, put on a inductive tach to adjust the POT and match the tach in the gauge set. Everything seemed to work other than.....
Keep getting code 61, bad #2 speed sensor. I tested the #2 sensor in trans, tests fine..... so i dont think it actually failed.

Theory, the cluster set out of the 88 3.0 V6 puts out a different speed sensor signal than it would if it was out of a 22RE....? So the ECT THINKS #2 sensor failed, (because the difference in signals) throws code 61, and is now running off the cluster sensor.

 

I don't think that's right. OR, the '88 is VERY different from the '93 and '94.

This is from the '93 FSM:


The #2 speed sensor in the transmission measures the speed the transmission turns. The #1 sensor (in your case in the cluster, by '93(?) in the transfer case itself) measures the speed the drive shaft turns AFTER the power goes through the transfer case. In 2Hi and 4Hi they're the same, but in 2Lo they are very different.

So #1 is what you want for the speedometer, and #2 is what you want for transmission shift points.

If the #2 sensor in your vehicle really is in the transfer case rather than the transmission, then what I just said won't help you.

 

scope103,
That is the other design, with the NO cable cluster. __Edit, going to add it to the top post for continuous info. If anybody knows the specific years they went to the electronic style let me know.

 

The procedure for testing the "reed switch" type of VSS1 (those with speedometer cable) is found in the FSM:
http://web.archive.org/web/201102052.../6combinat.pdf (There isn't much to it.)
There is no adjustment.

Ah, don't fall for that trap! Code 61 (I assume you mean TRANSMISSION code 61) is not "bad #2 sensor," it's "Defective No.2 vehicle speed sensor (in ATM)– severed wire harness or short circuit." http://web.archive.org/web/201408161...31diagnosi.pdf Testing the sensor itself is a good start, but the code means the signal is not getting to the ECM. The test procedure given in the FSM suggests checking the wiring at the ECM, then the sensor. (So you should probably now check the wiring.)

 

So I guess I should say how I tested #2 speed sensor. I tested it first at the plug, tested fine. Then I tested it also at the ECT Module to make sure its getting there, tested fine.

Then I tested under operating conditions, as the 1986 FSM says. Sp2 to ground voltage, it tested fine 4.8 or 0 still and 3.8 moving..... Also did the sp1 test at the ECT, its the same procedure as sp2, just 12v or 0v stand still, and 6v moving. Tested at 14v&0v stand still, and 5.8v moving.






Ok so I also did a couple other tests. I unhooked the SP1 wire from the ECT module and took it for a drive. As expected got a error 42 for the SP1 being unhooked. BUT did not trip a SP2 code 61.

Also took the old gauge set that doesnt have a tach installed it, took it for a drive. No code trips......but i didnt drive it that much.

 

Ok, so update.

Threw in a new speed sensor, still shifts the same, will drive it some more and see if it throws a code for the sensor again.

Im going to start a new thread relating to my shifting/ lockup problem and leave this one as just info towards the speed sensors.