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Overdrive switch

26K views 20 replies 7 participants last post by  Diefenbaker 
#1 ·
When I push the overdrive switch, the overdrive turns off. There is no light on the switch. I have replace the switch with one off my donor truck and the same thing happens. I am assuming that the light is burned out in both switches. The question I have is when you push the button again it will not turn the overdrive back on. The only way to turn it back on, is to turn off the truck with both switches. What else needs to be replaced to make this work right?

Second question. Since I have two switches, can i use the other switch to make it into a fog light switch. I'm not sure if it will work that way or not.
 
#2 ·
That is very odd. I am unsure what all is required when it switches on and off. also, it could be possible that there is a problem on your dash as far as the light not working.
 
#3 · (Edited)
This is the only light, I have a problem with now. All the other lights worked after I replaced all the missing ones that were pulled. Like my sig state, this is a beater truck and when I bought it, nothing worked, but with my donor truck, I have almost everything working again. The last I have to do is replace the speed sensor in the rear axle for the ABS light and brake light to go off and replace the clock spring in the steering wheel. Horn and cruse control do not work. I have these pulled from the donor truck but have not put them on yet.

I took apart the switch and the bulb is not burned out. Everything looked fine. What else do I need to take a look at? I see how it works. Inside the switch, when you push the switch in it makes contact with two metal pieces and shorts them. When your finger is released the contacts are no longer touching the button. To turn it off the same process is done. The same two contact are shorted. With that being said is there a relay somewhere that turn the OD on and off since the contacts are not constident shorted when it is off or on. If that make since.

I just do not know what is wrong with the Overdrive so I can pull that part before I get rid of my parts truck. Anyone know what I should try?
 
#5 ·
It will not go back into overdrive when you press the switch again. The only way to get it back into overdrive is to turn off the truck and it will reset it's self.
 
#6 ·
To me it sounds like there is a fault other then the switch. I could be wrong here, but just what i am thinking.
 
#9 ·
An overdrive off indicator is standard equipment
on all instrument clusters. However, on vehicles not
equipped with the optional overdrive automatic
transmission, this indicator is electronically disabled.
The overdrive off indicator is located near the lower
edge of the instrument cluster overlay, to the right of
center. The overdrive off indicator consists of a stencilled
cutout of the words “O/D OFF” in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from
being clearly visible when it is not illuminated. An
amber lens behind the cutout in the opaque layer of
the overlay causes the “O/D OFF” text to appear in
amber through the translucent outer layer of the
overlay when the indicator is illuminated from
behind by a Light Emitting Diode (LED) soldered
onto the instrument cluster electronic circuit board.
The overdrive off indicator is serviced as a unit with
the instrument cluster.
OPERATION
The overdrive off indicator gives an indication to
the vehicle operator when the Off position of the
overdrive off switch has been selected, disabling the
electronically controlled overdrive feature of the automatic
transmission. This indicator is controlled by a
transistor on the instrument cluster circuit board
based upon the cluster programming and electronic
messages received by the cluster from the Powertrain
Control Module (PCM) over the Chrysler Collision
Detection (CCD) data bus. The overdrive off indicator
Light Emitting Diode (LED) receives battery current
on the instrument cluster electronic circuit board
through the fused ignition switch output (st-run) circuit
whenever the ignition switch is in the On or
Start positions; therefore, the LED will always be off
when the ignition switch is in any position except On
or Start. The LED only illuminates when it is provided
a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
overdrive off indicator for the following reasons:
² Bulb Test - Each time the ignition switch is
turned to the On position the overdrive off indicator
is illuminated for about two seconds as a bulb test.
² Overdrive Off Lamp-On Message - Each time
the cluster receives an overdrive off lamp-on message
from the PCM indicating that the Off position of the
overdrive off switch has been selected, the overdrive
off indicator will be illuminated. The indicator
remains illuminated until the cluster receives an
overdrive off lamp-off message from the PCM, or
until the ignition switch is turned to the Off position,
whichever occurs first.
² Actuator Test - Each time the cluster is put
through the actuator test, the indicator will be
turned on during the bulb check portion of the test to
confirm the functionality of the LED and the cluster
control circuitry.
The PCM continually monitors the overdrive off
switch to determine the proper outputs to the automatic
transmission, then sends the proper messages
to the instrument cluster. For further diagnosis of
the overdrive off indicator or the instrument cluster
circuitry that controls the LED, (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). For proper diagnosis of the overdrive
control system, the PCM, the CCD data bus, or
the message inputs to the instrument cluster that
control the overdrive off indicator, a DRBIIIt scan
tool is required. Refer to the appropriate diagnostic
information.



This is from the factory service manual. Maybe this will help you out a little more.
 
#10 ·
Here is the overdrive wiring showing what signals it gets for it to work properly.
 

Attachments

#11 ·
OK, so now we are getting somewhere. Now in English, from what I am understanding from the above post, and with out testing it with a scanner, it looks like there is 4 posabilities. The switch, PCM, the speed sensor in the transmission, or a broken wire. So I have ruled out he switch (one down), I have a different PCM from my parts truck so I may switch that and see if that does anything, I will have to look to see if they are the same part number I have a 94 truck and this is a 95 parts truck, both 5.2. I already sold the speed sensor from the parts truck, oops. I will also look at the wiring under the transmission. I am assuming if there is a broken wire, that would be the place to start looking.

Thanks you very much JMW132001. This has been very helpful. Let me know if my thinking is wrong.
 
#12 ·
Not a problem. I am thinking the same as you as i have read through all of it and come up with the same possibilities.
 
#13 ·
Replaced the PCM today with the one on my parts truck. No change to the problem, I am thinking that it is the speed sencor in the transmission. That may be the reason why my ABS and Brake light are on too. 2 things down two more things to check.
 
#14 ·
When the speed sensor on my truck went out on the transmission it caused my speedo to be off by like 5mph and the check engine light come on. Now, whenever my abs and brake light come on, it was the sensor located on the top of the rear diff that caused that.
 
#15 ·
Have you tried to hook up a scanner and see if there are any stored codes that might help. I have a bad sensor that doesn't throw a code and have similar problems but it works sometimes and doesn't other times.
 
#17 ·
I have never hooked up a scanner to it. Don't have one and just have not took it anywhere.

I have two spare gage clusters so, maybe I will try that. Did not know they stored codes.

I changed the PCM today and it did not do any thing, all the same lights were still on and the OD did the same thing. I only drove around the block and then changed it back. The part number did not match up. It did still run fine. I really think it is a speed sensor in the transmission. That is the only thing left except the gage cluster, if it holds codes or a broken wire.
 
#18 ·
That seed sensor is only 10-15 bucks and takes 5 minutes to replace. Just make sure you unplug battery while you do it so pcm resets. then give it a shot.
 
#19 ·
I thought on the 94-97 trucks, the indicator light he is talking about is actually located in the button, on the dash. 98-01/02 trucks had the light in the cluster.

A guy I work with was having O/D problems, long story short it was a speed sensor. I dont remember if it was the front or rear sensor tho. . .
 
#20 ·
I replaced the speed sensor it the rear axle today. No more ABS light or brake light. They both went off. (I love having a parts truck.) The OD still will not turn back on, so it was not the rear sensor. The last thing to change is the speed sensor in the front. Hopefully I can get one tomorrow from the parts store.

The switch for the OD is located on the dash.
 
#21 ·
I attached the wiring for the overdrive switch out of a 97 Ram service manual. It should be the same as for the 94.

The over drive switch is a pushbutton. Every time you press the button it will gives ground to the PCM. The PCM gives you feedback when the overdrive is off via the indication lamp in the switch. For that the PCM provides ground to pin 5 of the overdrive switch.
With disconnected switch you can first check if there is ground on pin 2 of the overdrive switch connector and as 2nd check if there is power on pin3 when the engine is running.
 
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