L/U and O/D switches with LED wiring. Paging the usual sparkys

bateman

bateman

Active member
After a couple years on the shelf I got my B&M gated shifter installed. After taking a test drive I realize lockup is not happening. (1k ohm resistor in temp sensor, stock TPS and PCM) possibly a random problem showing it’s face after the shifter but I’ve checked everything. Only thing that I changed was removing the stock shift lever and replacing it with one for the cable. TV lever and adjustment did not change.

Moving on, I decide to go ahead and wire the Billet Automotive Buttons up that are installed in the shifter. They are lit with an LED when activated. My question is very basic and I assume I will be called a retard which is fine ha.

Trans is a 47RH (94-95). Can I wire these buttons up like so? Three wire plug on trans. Middle is power in. Outside wires are too ground for L/U and O/D. Can I put the switch on the ground wire with the LED wired on the same circuit. My thinking is there is always 12v going in, then I ground it to activate L/U or O/D and the circuit is completed for the light as well?

I ask this because I read something about a light back feeding to the PCM or something and I can’t understand how. Maybe that was for incandescent bulbs?

I understand this may not fix my problem. Could be a lock up solenoid failure or broken wiring harness. Just curious about the wiring for the switches as that will tell me if I have other issues. Right now I’m going to hope it’s the TPS.
 
bateman said:
After a couple years on the shelf I got my B&M gated shifter installed. After taking a test drive I realize lockup is not happening. (1k ohm resistor in temp sensor, stock TPS and PCM) possibly a random problem showing it’s face after the shifter but I’ve checked everything. Only thing that I changed was removing the stock shift lever and replacing it with one for the cable. TV lever and adjustment did not change.

Moving on, I decide to go ahead and wire the Billet Automotive Buttons up that are installed in the shifter. They are lit with an LED when activated. My question is very basic and I assume I will be called a retard which is fine ha.

Trans is a 47RH (94-95). Can I wire these buttons up like so? Three wire plug on trans. Middle is power in. Outside wires are too ground for L/U and O/D. Can I put the switch on the ground wire with the LED wired on the same circuit. My thinking is there is always 12v going in, then I ground it to activate L/U or O/D and the circuit is completed for the light as well?

I ask this because I read something about a light back feeding to the PCM or something and I can’t understand how. Maybe that was for incandescent bulbs?

I understand this may not fix my problem. Could be a lock up solenoid failure or broken wiring harness. Just curious about the wiring for the switches as that will tell me if I have other issues. Right now I’m going to hope it’s the TPS.
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I had the same problem when I first installed my mvb auto. The LED/resistor for it has too much resistance on the ground side. Eliminate the LED and I bet the problem is gone. You wont have any trouble telling when you are in lockup and overdrive.
 
Thanks Vince. So I was not completely clear as usual ha. I haven’t wired the switches yet. Was just curious if it would work or do as you said. Figured a led wouldn’t draw much.

The problem with lockup currently is my brake switch. Just went to lunch and lifted the brake pedal and bam lockup. The fact it happened with the truck cut off and me hooking a shifter up is just my luck.

So do you think there is any way to wire the led up without using relays? Hoped to keep it simple.
 
bateman said:
Thanks Vince. So I was not completely clear as usual ha. I haven’t wired the switches yet. Was just curious if it would work or do as you said. Figured a led wouldn’t draw much.

The problem with lockup currently is my brake switch. Just went to lunch and lifted the brake pedal and bam lockup. The fact it happened with the truck cut off and me hooking a shifter up is just my luck.

So do you think there is any way to wire the led up without using relays? Hoped to keep it simple.
Click to expand...
Nah, is you put the LED on the ground side of the switches, it will never light, if you add resistance to the other ground path, the solenoids won't function. Easiest is wire the switches through the control side of the relays and get what you want.

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biggy238 said:
Nah, is you put the LED on the ground side of the switches, it will never light, if you add resistance to the other ground path, the solenoids won't function. Easiest is wire the switches through the control side of the relays and get what you want.

Sent from my motorola one 5G using Tapatalk
Click to expand...

Alright thanks guys. I will study that setup for a bit before any questions to keep it fair. If I had just toggles I wouldn’t mind but these buttons are too slick to not have lights working right.
 

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i messed with this awhile back, i had them in series with the solenoids themselves and the LEDs would only work 1 or 2 times before they got burnt up. ended up having to add flyback diodes and then it worked. But i was not using relays,just 12v to the one side of the switch,and the other side going down to the 8 pin plug on the trans with the led inbetween the switch and the round 8.wire 7 and 8 for lockup and od if i remember correctly(which i prolly dont as it was 7 or 8 years ago)
 
It's one of those ask 20 people and get 20 answers deals.
I don't know how the lights are wired, are they separate circuits from the switches themselves? Could be single source and one path through the switch and one through the LED.
The biggest issue I had running manual lockup is that I would forget to unlock or have a hard braking event. If I were doing it again, I would run 3 relays, one for LU, one for OD, and one tied to the brake to interrupt the gnd path of the LU circuit so if you hit the brakes it unlocks.
Busman makes some nice relay banks to do this with. I may see about getting my hands on one and making it plug and play. Info t have anything to test on. Not that it would need to be.

Could use these


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Haha we were three deep headed to the beach when I took the pic.

Good info. So the voltage spike will kill the light without fly back diodes. Did you test l/u and o/d function of the switches on the street? Curious about the resistance mentioned above and if it’s a problem with these small leds
 
Biggy that’s the one thing I don’t like. Might end up doing it like you say through the brake circuit. I’ll find the info on the switches. They are kind of a pain in the ass over just running some toggles, but I wanted them haha
 
Found this one. I’m just curious about the positive wire for the accessory which would be the solenoids.
 

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Or maybe it’s the positive switching? Ha man I wish I was better with wires.
 

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I told you.... 20 ppl.

87 and 30 connect when the relay is energized. It doesn't matter which poles you connect to as long as one is trans and the other is gnd.

85 and 86 matter. If the relays have flyback diodes, trigger needs to be on 85 and gnd needs to be on 86.

I personally would feed 12 to the switch and the high side of the LED, and let pin 85 be the Union point for them both. That should light the LED whenever the relay is energized.

Edit: that's what your second image is showing. Just swap 87 and 30 for your lockup and od circuits

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Awesome. Thank you. I may be back ha but I will try to wrap my head around this and attempt it first.
 
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