The best way to check both would be with a good volt ohm meter the switch will be open when not in reverse and closed when in reverse that s where i would start anyway.
Allison automatic transmission reverse light switch location.
Part number ms27145 10 is the connector plug pigtail harness for this backup reverse light switch part number 29503665ak is the part number for the plug and pigtail assembly.
We bought it second hand and it is not equipped with reverse triggered back up lights or beeper.
Your allison md 3066 does not have a back up switch the signal is sent by the allison ecu to an oem relay which turns on your back up lights i would suggest locating the relay center and finding a relay marked reverse warning you can swap it with another same relay to verify the relay itself is bad.
Park neutral and gear selector position info on these transmissions is done with an internal mode switch ims mounted on the rooster comb inside the transmission.
Replacing a backup light switch is fairly straightforward if you know what the switch looks like and where to locate it on your vehicle.
A backup light switch screws into the transmission and is triggered when you shift the vehicle into reverse.
Need to replace your vehicle s reverse light switch.
I m working on a 2006 capacity yard tractor.
I would start with tracing the wiring from the bulb back to the switch which will be located on the top of the transmission if the wiring is good it is probably the switch.
If the switch is functioning normally a circuit is completed when the switch is triggered and the white lights in the tail lights will illuminate.
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Found on allison at540 at542 at545 mt640 mt643 mt644 mt647 mt650 mt653 mt653 ht740 and other ct clbt and ht700 series transmissions.
Any idea where to wire lights from.
Its functions are brought out through the 20 pin connector on the transmission see above.
1a auto has aftermarket reverse light switches for many cars trucks suvs and vans and ground shipping is always free.
The price for oem is over 100 and the napa switch is like 8 bucks.
Over the past several years i have been using a pressure switch from napa to replace the back up light switch on these older allison transmissions.
Then shop at 1a auto for a replacement backup light lamp switch at a great price.
