Installing a transmission temperature guage in a 42RLE

Irun

A vicious cycle of doing, undoing, and re-doing!
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In the event someone else is interested, I recently installed an updated transmission temperature gauge in my LJ. Since I couldn't find a comprehensive set of instructions, I thought I'd share what I did. The install involved replacing the stock 42RLE transmission pan with one that has a drain plug in it. The process was basically the following:

Remove the engine skid, if you have one, and support the transmission with a jack stand
Remove the transfer case skid plate (Make sure step one is done first!!!!)
Remove the stock transmission pan
Remove the old filter and install a Mopar replacement filter (don't forget the o-ring)
Clean up the transmission gasket surface - The factory uses RTV and not a gasket. Instead of using RTV, I use a reusable LubLocker gasket.
Install the the replacement pan and LubeLocker gasket and torque the bolts to spec (14.5ft lbs). Note: I use Blue Loctite on the pan bolts to keep them from loosening.
Install the M14 1.5 to 1/8 brass sensor adapter in the pan
Install the temperature sensor into the adapter
Install the Gauge and wiring
Fill the transmission with ATF 4+
Start and check for leaks (Address any leaks as needed), and check that the temperature gauge is functioning
Re-install the transfer case skid plate and remove the jack
Re-install the engine skid (If you have one)

When doing the wiring I removed the manual transmission block off plate, located on the drivers side next to the brake booster, and used a Daystar Firewall boot to run the wiring through. To make this happen I drilled a 1.25" hole in the block off plate and pulled the Daystar boot through from the inside out. I ran the wiring from the sending unit, installed 1/4" wire loom, then taped that and pulled it through the firewall boot. Once that was done I connected the wires to the gauge.

The parts list is the following:

Dorman 265-818 Transmission Pan (with drain plug)
https://www.amazon.com/gp/product/B00Z7O4OVA/?tag=wranglerorg-20

Mopar 6805 9549AA, Auto Trans Filter
https://www.amazon.com/dp/B00F6E49UW/?tag=wranglerorg-20

Lube Locker LLT-A042 transmission pan gasket
https://www.amazon.com/gp/product/B00BOU6UJA/?tag=wranglerorg-20

Auto Meter 2267 Oil/Temperature Metric Adapter (M14 1.5 to 1/8)
https://www.amazon.com/gp/product/B00062YVOI/?tag=wranglerorg-20

MaxTow Double Vision 260 F Transmission Temperature Gauge Kit - Includes Electronic Sensor - Black
https://www.amazon.com/gp/product/B01MS4HDXC/?tag=wranglerorg-20

1.3 Gallons of Mopar ATF 4+
https://www.amazon.com/gp/product/B00HN4GTQK/?tag=wranglerorg-20

Daystar Firewall Boot KU20040BK
https://www.amazon.com/gp/product/B004K2285E/?tag=wranglerorg-20

Auto Meter 2204 Mounting Cup
https://www.amazon.com/gp/product/B0009RUXPG/?tag=wranglerorg-20

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Last edited:
Nice write up. (y)

Added a gauge to mine too a couple years ago. I used One of those kits where you drill a hole, installed the bung and washers and nut in the inside of the pan. i also added one for a separate drain plug. The temp sensor has been fine, but the drain plug leaks a little bit. I recently bought that same dorman pan and a weld in 1/8 NPT bung that I’ll going to get a buddy weld in for me. I read reviews on amazon that people’s drain plugs leaked. I did like someone else and replaced the copper washer with one of those blue nylon ones. Let it sit for 3 days with a little trans fluid in the pan and had no leaks at all. Hopefully I get the welding done this weekend. When I changed the filter last, I too used a lube locker gasket, so I’m looking forward to the ease of replacement. : )
 
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That firewall boot idea through the plate is clever as hell and looks very clean.
 
This is great. Do you have any pics of the installation under your Jeep? Trying to imagine how far the sensor sticks out, does it come close to hitting anything, like the skid? How did you route the wires?
 
Awesome write up! I'm about to flush the tranny fluid on the LJ and TJ and I was thinking about adding a temp sensor, gauge, and maybe a cooler. This will make it so much easier. Thanks for sharing. I'm also curious about how close the sensor is to the skid if you or anyone else who has done something similar has any pics.
 
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Awesome write up! I'm about to flush the tranny fluid on the LJ and TJ and I was thinking about adding a temp sensor, gauge, and maybe a cooler. This will make it so much easier. Thanks for sharing. I'm also curious about how close the sensor is to the skid if you or anyone else who has done something similar has any pics.
This is great. Do you have any pics of the installation under your Jeep? Trying to imagine how far the sensor sticks out, does it come close to hitting anything, like the skid? How did you route the wires?
I looked to see if I had any pictures, but didn't. I'll get one over the next couple days. That said, I had no clearance issues between the UCF transmission/engine skid that is installed.
 
I looked to see if I had any pictures, but didn't. I'll get one over the next couple days. That said, I had no clearance issues between the UCF transmission/engine skid that is installed.
Thanks. I ended up just plumbing it in-line after the Derale cooler. It’s cool to see it working - when the needle goes just above 180, the fan kicks on, then temp gradually drops back down to 170.
 
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In the event someone else is interested, I recently installed an updated transmission temperature gauge in my LJ. Since I couldn't find a comprehensive set of instructions, I thought I'd share what I did. The install involved replacing the stock 42RLE transmission pan with one that has a drain plug in it. The process was basically the following:

Remove the engine skid, if you have one, and support the transmission with a jack stand
Remove the transfer case skid plate (Make sure step one is done first!!!!)
Remove the stock transmission pan
Remove the old filter and install a Mopar replacement filter (don't forget the o-ring)
Clean up the transmission gasket surface - The factory uses RTV and not a gasket. Instead of using RTV, I use a reusable LubLocker gasket.
Install the the replacement pan and LubeLocker gasket and torque the bolts to spec (14.5ft lbs). Note: I use Blue Loctite on the pan bolts to keep them from loosening.
Install the M14 1.5 to 1/8 brass sensor adapter in the pan
Install the temperature sensor into the adapter
Install the Gauge and wiring
Fill the transmission with ATF 4+
Start and check for leaks (Address any leaks as needed), and check that the temperature gauge is functioning
Re-install the transfer case skid plate and remove the jack
Re-install the engine skid (If you have one)

When doing the wiring I removed the manual transmission block off plate, located on the drivers side next to the brake booster, and used a Daystar Firewall boot to run the wiring through. To make this happen I drilled a 1.25" hole in the block off plate and pulled the Daystar boot through from the inside out. I ran the wiring from the sending unit, installed 1/4" wire loom, then taped that and pulled it through the firewall boot. Once that was done I connected the wires to the gauge.

The parts list is the following:

Dorman 265-818 Transmission Pan (with drain plug)
https://www.amazon.com/gp/product/B00Z7O4OVA/?tag=wranglerorg-20

Mopar 6805 9549AA, Auto Trans Filter
https://www.amazon.com/dp/B00F6E49UW/?tag=wranglerorg-20

Lube Locker LLT-A042 transmission pan gasket
https://www.amazon.com/gp/product/B00BOU6UJA/?tag=wranglerorg-20

Auto Meter 2267 Oil/Temperature Metric Adapter (M14 1.5 to 1/8)
https://www.amazon.com/gp/product/B00062YVOI/?tag=wranglerorg-20

MaxTow Double Vision 260 F Transmission Temperature Gauge Kit - Includes Electronic Sensor - Black
https://www.amazon.com/gp/product/B01MS4HDXC/?tag=wranglerorg-20

1.3 Gallons of Mopar ATF 4+
https://www.amazon.com/gp/product/B00HN4GTQK/?tag=wranglerorg-20

Daystar Firewall Boot KU20040BK
https://www.amazon.com/gp/product/B004K2285E/?tag=wranglerorg-20

Auto Meter 2204 Mounting Cup
https://www.amazon.com/gp/product/B0009RUXPG/?tag=wranglerorg-20

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Thanks! I’m about to change the fluid in the twins 42rle. The Dorman pan with drain plug will be a sigh of relief!
 
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I would add that wiring in a weather proof plug near the temp sender is very handy in the event you ever need to drop your transmission or do work on the harness. It's nice to be able to unplug it rather than cut the wires or remove the sender from the pan.
 
In the event someone else is interested, I recently installed an updated transmission temperature gauge in my LJ. Since I couldn't find a comprehensive set of instructions, I thought I'd share what I did. The install involved replacing the stock 42RLE transmission pan with one that has a drain plug in it. The process was basically the following:

Remove the engine skid, if you have one, and support the transmission with a jack stand
Remove the transfer case skid plate (Make sure step one is done first!!!!)
Remove the stock transmission pan
Remove the old filter and install a Mopar replacement filter (don't forget the o-ring)
Clean up the transmission gasket surface - The factory uses RTV and not a gasket. Instead of using RTV, I use a reusable LubLocker gasket.
Install the the replacement pan and LubeLocker gasket and torque the bolts to spec (14.5ft lbs). Note: I use Blue Loctite on the pan bolts to keep them from loosening.
Install the M14 1.5 to 1/8 brass sensor adapter in the pan
Install the temperature sensor into the adapter
Install the Gauge and wiring
Fill the transmission with ATF 4+
Start and check for leaks (Address any leaks as needed), and check that the temperature gauge is functioning
Re-install the transfer case skid plate and remove the jack
Re-install the engine skid (If you have one)

When doing the wiring I removed the manual transmission block off plate, located on the drivers side next to the brake booster, and used a Daystar Firewall boot to run the wiring through. To make this happen I drilled a 1.25" hole in the block off plate and pulled the Daystar boot through from the inside out. I ran the wiring from the sending unit, installed 1/4" wire loom, then taped that and pulled it through the firewall boot. Once that was done I connected the wires to the gauge.

The parts list is the following:

Dorman 265-818 Transmission Pan (with drain plug)
https://www.amazon.com/gp/product/B00Z7O4OVA/?tag=wranglerorg-20

Mopar 6805 9549AA, Auto Trans Filter
https://www.amazon.com/dp/B00F6E49UW/?tag=wranglerorg-20

Lube Locker LLT-A042 transmission pan gasket
https://www.amazon.com/gp/product/B00BOU6UJA/?tag=wranglerorg-20

Auto Meter 2267 Oil/Temperature Metric Adapter (M14 1.5 to 1/8)
https://www.amazon.com/gp/product/B00062YVOI/?tag=wranglerorg-20

MaxTow Double Vision 260 F Transmission Temperature Gauge Kit - Includes Electronic Sensor - Black
https://www.amazon.com/gp/product/B01MS4HDXC/?tag=wranglerorg-20

1.3 Gallons of Mopar ATF 4+
https://www.amazon.com/gp/product/B00HN4GTQK/?tag=wranglerorg-20

Daystar Firewall Boot KU20040BK
https://www.amazon.com/gp/product/B004K2285E/?tag=wranglerorg-20

Auto Meter 2204 Mounting Cup
https://www.amazon.com/gp/product/B0009RUXPG/?tag=wranglerorg-20

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Any direction as to the wiring?
 
I ran the wires from the sender up over the transmission and through the firewall around the area of the heater core tubes. My gauge needed signal, ground, +12V switched and +12V constant (I have a Glowshift [no complaints after 2 yrs] that needs to remember what color you had it set on). I think I used a tap a fuse on the radio (switched) & foglamp (constant) circuits. I tied the sender ground to the gauge ground and connected them both to the big lug on the dashboard frame behind the gauge cluster. You might pick a different ground if you're mounting it on the trans console.

{I say "think" I used tap-a-fuses because I know I made use of them on switch panel project, but I installed the gauge well before then and I'm pretty sure I didn't introduce the fuse taps until I wired in the switch panel.}

I also wired a weather proof connector about 12" from the sending unit so that I can unplug it whenever I drop the pan. I know I intended to wire in a plug behind the dash to make it easy to take things apart later but I'm confident I never got around to that. Be sure to put some loom around the wires, it gets hot down there and there is some spinny stuff.
 
I ran the wires from the sender up over the transmission and through the firewall around the area of the heater core tubes. My gauge needed signal, ground, +12V switched and +12V constant (I have a Glowshift [no complaints after 2 yrs] that needs to remember what color you had it set on). I think I used a tap a fuse on the radio (switched) & foglamp (constant) circuits. I tied the sender ground to the gauge ground and connected them both to the big lug on the dashboard frame behind the gauge cluster. You might pick a different ground if you're mounting it on the trans console.

{I say "think" I used tap-a-fuses because I know I made use of them on switch panel project, but I installed the gauge well before then and I'm pretty sure I didn't introduce the fuse taps until I wired in the switch panel.}

I also wired a weather proof connector about 12" from the sending unit so that I can unplug it whenever I drop the pan. I know I intended to wire in a plug behind the dash to make it easy to take things apart later but I'm confident I never got around to that. Be sure to put some loom around the wires, it gets hot down there and there is some spinny stuff.

Thank you. Very helpful. Do you know what size fuses you used in the fuse taps? The instructions don't address it.
 
Thank you. Very helpful. Do you know what size fuses you used in the fuse taps? The instructions don't address it.

you have to use the same size or smaller in the tap, since it's running though the same circuit you're tapping into (and also correctly sized for whatever accessory you're adding). It will say what size each fuse is on the box behind the glove box. 10A should be more than enough though.
 
In the event someone else is interested, I recently installed an updated transmission temperature gauge in my LJ. Since I couldn't find a comprehensive set of instructions, I thought I'd share what I did. The install involved replacing the stock 42RLE transmission pan with one that has a drain plug in it. The process was basically the following:

Remove the engine skid, if you have one, and support the transmission with a jack stand
Remove the transfer case skid plate (Make sure step one is done first!!!!)
Remove the stock transmission pan
Remove the old filter and install a Mopar replacement filter (don't forget the o-ring)
Clean up the transmission gasket surface - The factory uses RTV and not a gasket. Instead of using RTV, I use a reusable LubLocker gasket.
Install the the replacement pan and LubeLocker gasket and torque the bolts to spec (14.5ft lbs). Note: I use Blue Loctite on the pan bolts to keep them from loosening.
Install the M14 1.5 to 1/8 brass sensor adapter in the pan
Install the temperature sensor into the adapter
Install the Gauge and wiring
Fill the transmission with ATF 4+
Start and check for leaks (Address any leaks as needed), and check that the temperature gauge is functioning
Re-install the transfer case skid plate and remove the jack
Re-install the engine skid (If you have one)

When doing the wiring I removed the manual transmission block off plate, located on the drivers side next to the brake booster, and used a Daystar Firewall boot to run the wiring through. To make this happen I drilled a 1.25" hole in the block off plate and pulled the Daystar boot through from the inside out. I ran the wiring from the sending unit, installed 1/4" wire loom, then taped that and pulled it through the firewall boot. Once that was done I connected the wires to the gauge.

The parts list is the following:

Dorman 265-818 Transmission Pan (with drain plug)
https://www.amazon.com/gp/product/B00Z7O4OVA/?tag=wranglerorg-20

Mopar 6805 9549AA, Auto Trans Filter
https://www.amazon.com/dp/B00F6E49UW/?tag=wranglerorg-20

Lube Locker LLT-A042 transmission pan gasket
https://www.amazon.com/gp/product/B00BOU6UJA/?tag=wranglerorg-20

Auto Meter 2267 Oil/Temperature Metric Adapter (M14 1.5 to 1/8)
https://www.amazon.com/gp/product/B00062YVOI/?tag=wranglerorg-20

MaxTow Double Vision 260 F Transmission Temperature Gauge Kit - Includes Electronic Sensor - Black
https://www.amazon.com/gp/product/B01MS4HDXC/?tag=wranglerorg-20

1.3 Gallons of Mopar ATF 4+
https://www.amazon.com/gp/product/B00HN4GTQK/?tag=wranglerorg-20

Daystar Firewall Boot KU20040BK
https://www.amazon.com/gp/product/B004K2285E/?tag=wranglerorg-20

Auto Meter 2204 Mounting Cup
https://www.amazon.com/gp/product/B0009RUXPG/?tag=wranglerorg-20

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Great write up. I have one suggestion, the wire loom running down to the factory wire grommet needs a drip loop in it. I have seen way to many water leaks from add on wiring harnesses without a drip loop. Many running down under the carpeting and soaking the insulation.
 
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Great write up. I have one suggestion, the wire loom running down to the factory wire grommet needs a drip loop in it. I have seen way to many water leaks from add on wiring harnesses without a drip loop. Many running down under the carpeting and soaking the insulation.

Good suggestion. I'll take a look and see about adding one.
 
Installed the glow shit gauge referenced in OP. It lights up, but only reads 80 degrees. Never moves. Probe mounted in pan. So far glow shift tech support is not helpful.