Need help identifying switch on transmission
 

Need help identifying switch on transmission

Started by richard5933, March 23, 2019, 09:23:56 AM

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richard5933

On our Spicer 4-speed there is a switch mounted just below the reverse solenoid. Looks like an oil pressure switch. It's not the transmission oil pressure switch though, as that is mounted by the trans oil filter. Two wires coming from it.

Anyone know what this is?

I ask because it's got a slow drip of oil from it and I want to replace it. Got to know what it is though. Picture to follow momentarily.
Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin

luvrbus

Backup lights or low pressure warning for the transmission pump
Life is short drink the good wine first

richard5933

Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin

Bill Gerrie

Turn on the ignition and touch the two wires together and see if the back up lights come on. Also might check if you get a low oil warning inside or if you are getting a low oil warning see if it goes out when you touch the wires together.

chessie4905

Since it is at the top of the shift tower, it would be for back up lights. The 4104 used to have one by the transmission oil pump for low oil pressure.Does yours have this also? If it does, it would be mentioned in the operators manual.
GMC h8h 649#028 (4905)
Pennsylvania-central

richard5933

Quote from: chessie4905 on March 23, 2019, 10:13:59 AM
Since it is at the top of the shift tower, it would be for back up lights. The 4104 used to have one by the transmission oil pump for low oil pressure.Does yours have this also? If it does, it would be mentioned in the operators manual.

There is another switch with a single wire mounted next to where the trans oil filter is mounted. According to the manual that one is for the low pressure light. Makes sense that the switch in question is for the backup lights then.

Thanks for the clarity on this.

On a related subject, since the picture shows it so clearly, anyone found a better rubber boot for the reverse solenoid? You can see what happened to mine - this one only lasted about 8 months. The one before that only about 4.
Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin

akroyaleagle

Joe Laird
'78 Eagle
Sioux Falls, South Dakota

richard5933

Quote from: akroyaleagle on March 28, 2019, 04:04:33 PM
Do you have a transmission temp gauge?

No such gauge.

Luke agreed that this is most likely the switch for the reverse lights. I'll know for sure when the replacement arrives tomorrow.
Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin