TESTING CENTER DIFF LOCK SWITCH/HARNESS (1 Viewer)

[ParadiseCruiser]

Matt, Dan -

No wonder people think we're weird: eating supper with an automobile schematic spread out on the table!

Well, the kludge of a scotch-lock certainly was unexpected. As to predicting what actually transpired here, it's very difficult to guess. I'm not one for jumping to conclusions so quickly, but Dan could be right. The real problem is that the harness with the S10 plug on it (where the center diff lock switch or, alternatively the shorting plug goes), among a couple of other harnesses on these trucks, is not in the U.S. schematics, so there is no way to logically follow the circuit to give an educated guess.

I will look at this further and, if I can add something constructive, will report back...

R -

 

[ParadiseCruiser]

M -

  In the mean time, there is something else you can do. Get out the trusty multimeter, and pull the DS kick panel to gain access to the center diff lock control relay...

  1. Set meter on ohms, ground one probe and put the other probe on pin 2 of the relay: You should see full continuity (i.e., full meter swing, same as if you shorted the two probes together);

  2. Set meter to DC volts, ground the Neg probe and put the Pos probe on pin 3 of the relay :: turn the ignition key ON (engine OFF): You should see approx 12 v here. If not, pull the 30A center diff fuse in the DS lower dash panel, check / replace it;

  3. Still on DC volts, ground the Neg probe and put the Pos probe on pin 7 of the relay :: Ignition ON,  Engine OFF,  Transfer case lever in Low: You should see approx 12 v here as well.

4. Finally, in the DS lower dash panel, pull and check / replace the 10A gauge fuse (middle row, 2nd from the top). This fuse powers the center diff light in the dash as well as the S10 plug).

  What you're doing here is confirming that the relay is getting all the signals it expects to see. Until all these check out ok, it's premature to be saying any prayers for the relay itself...

 R -

 

[Beowulf]

>> I had an issue with the switch about <<
>> a year ago and Toyota must have put <<
>> the blue splice in. <<

Ahhhhh, the plot thickens.

You're in good hands with Dan and Ron helping you on this. Hang in there, give them good accurate information, and you'll get this working properly.

-B-

 

[Beast II]

It looks like the Transmission Relay is fried. I ordered another one - cost $132.00 A heck of alot better than $1500+ for the main ECU. So that I don't fry this Transmission Relay as well, is there a particular way to install it ?

Thank you for all of the help,

Matt

 

[cruiserdan]

Matt,
That is a very fair price. As far as installing it, make sure that you have removed that GD scotchlock from the CDL switch plug and the wires are ok. Put the CDL switch back in and put the new relay in. You should be good to go from there.

Ron, Do you agree?
Matt, let's wait for Ron to toss in here before you go ahead with it.

Regards.....Dan

 

[ParadiseCruiser]

Matt -

I basically agree with Dan on this. My only concern - if it were my truck - is that previous events may have created a short in the harness and that it would, in turn, fry the new relay as well.

I would at least attempt to eliminate the obvious - as best as that may be possible...

1. After removing the scotch-lock jumper, check the wires physically to determine if there is any damage, bare spots that could create a problem, etc;
2. Using a high resistence scale on your meter, check the various pins on the plug for obvious shorts...
a. for continuity across pins 7 & 10 to make sure they are not shorted;
b. for continuity between pin 7 to ground, and also pin 10 to ground. Same thing: make sure they are not shorted to ground;
c. for continuity between pin 7 and all of the others, and between pin 10 and all of the others for obvious shorts. (This one may be tricky, because admittedly - without a schematic, it's difficult to predict what you will find);
3. With ignition on (engine off), make sure you see 12v on pin 7 (measured to ground) - and that you do not see 12v on pin 10.

If you find anything particularly suspicious, pull the connectors on the old relay, and measure again... to determine if the effect is due to a fried circuit in the relay.

That's really all I can think of, assuming of course that the diff actuator and sensing switch down below are ok.

Good luck !

R -

 

[cruiserdan]

Amen..........

 

[Beast II]

Finally got the new diff lock relay and am still having problems - ie. no lights go on on the dash and diff lock doesn't engage. When pushing the switch, I hear a click from the relay and what sounds like the actuator engaging and disengaging and I hear a click from the new relay too - but nothing happens. I'm buying a multimeter today and will do as Paradise advised. Any simple - "How to use a multimeter" websites you guys know of ?

Thank you

Matt

 

[Beast II]

Could this be a bad transfer indicator switch on top of the transfer case ?

http://www.sleeoffroad.com/technical/tz_centerdiff.htm

 

[Beast II]

Well, finally - It was a bad transfer indicator switch on top of the transfer case. What an easy thing to fix though. About 10 minutes with a cresent wrench and $51.00 for the part and now the diff lock switch will activate in high and low.