I installed an oil pressure gauge while I was replacing the head gasket last month and super wish I had done this earlier. Really nice to have an eye on that measurement. So far it's been 50 or in the upper 40s when cold, and then upper 40s when warm and motoring around town. Warm idle is in the 10s. Nice to see. But also expected - I replaced the oil pump preventatively while changing the front timing cover last summer.

I just used the empty port on the front cover above the oil pressure switch, but I actually switched the oil pressure switch and moved it to the blank spot, and then put the gauge sending unit where the switch was. Had to do this for clearance with the alternator bracket assembly. I had to use an adapter that made it a bit longer.

If anyone is wanting to do this too, I just got everything off Amazon:

Adapter to adapt pressure sending unit to empty oil port: https://amzn.to/3tY62Fj
Gauge: https://amzn.to/3q8j3Ly
Gauge holder (I cut off an inch off the back to make it more compact): https://amzn.to/3icWJvW

 

Love it. I’ve been meaning to do this for a while.

 

did you plug that into the oil cooler ports ?

 

No, those are farther south on the front cover than these two ports.

 

Well done. I did a sandwich one on the oil filter on the last D2. It was fine, but did make the oil changes take a few more minutes. Readings were very much what they should have been,

 

Can you tell me which wire you used to connect to the "headlamp" circuit so it dims along with the dashboard lighting when the headlights are switched on? Or did you opt not to do this so it stays bright at all times? I've been confused about which wire to cut and don't want to cut the wrong one - from the best of my manual and wiring diagram reading, it'll be a blue/red wire, but I'm probably very wrong...

 

The dimmer function wire on the gauge I installed is orange, and the orange wire goes into Fuse 11, which is the headlights fuse. Also, no need to cut wires, just get these little fuse pigtails. The whole installation can be fully undone and isn't destructive.

Also, I use Wago lever nuts whenever I do wiring. Super easy to install and undo if needed.

Here's a link to the gauge: https://amzn.to/3wmBsGJ
Wago: https://amzn.to/3sw6CKy

 

Thank you - I’m guessing yours is also the GlowShift gauge since the orange wire is for the dimming function on the one I’ve got too.

From the manual, I believe the 03 D2 has the same fuses in F11 and F26.

F11 shows “Header 286” - I guess it measures 12V and controls the dash dimming, so I’ll use that for the orange wire?

I’m wondering about F26 (looks like you’re using that fuse) - “Auxiliary relay” - is that the 12V switched source that’s on only when the key is turned to the “radio on” position? Or maybe it’s the constant 12V like the clock? So that would be the red wire if it’s the switched source and yellow wire if it’s the constant.

Are you using another add-a-circuit pigtail wire in the fuse box for the third connection or is that being done with the Wago connector? I’m unsure where the wago connector would be in your setup.

Can you tell me where you grounded the unit as well?

I’d really appreciate any help! Hoping to start up with the gauge working since I’m replacing the oil pump and it’ll be critical to see what’s going on right away.

 

Yep, sounds like the same gauge. I linked my gauge above so you can double check.

I cheated a bit with the constant (yellow) wire. My 2002 came with the factory safari lights that had a stock wiring loom that ran through the bulkhead up to a relay right beside the battery and fuse box. The fuse stopped working ages ago (they don't last long) so I took the constant that fed the relay and connected it to the yellow wire. When I do this to my 2004 (that doesn't have this safari light relay), I'll run a direct wire straight from the battery.

Wago usage is just in place of a wire nut. It's used to connect the add-a-circuit (AAC) pigtail to the gauge wire. It's not necessary, just very easy and very secure. I have a ton on-hand anyway from a huge wiring project (building a house).

There are only two AAC's used in the fuse box.

Fuse 26 is where I connected the red wire from the gauge.

For the ground, I cheated again and used the ground wire from that safari light relay which is up by the fuse box in the engine bay. I ran a really long wire from there back to the gauge. When I do it to the 2004, I'll use the same lug since I'm already running a wire from the battery for a constant 12v, and it's way way easier to access than any of the ground nuts under the dash.

So to sum up, ground wire and constant wire go from the battery area, through the wiring harness that goes over the engine, and then through the bulkhead to the gauge. Wago nuts connect the gauge wires to these two wires (I bought bulk wire from Napa for those long runs). The AAC at Fuse 26 gets connected (I used a Wago nut) to the red wire on the gauge. The AAC on Fuse 11 gets connected to the orange wire on the gauge. Make sense?

 

Thank you - that helps me a lot. I don’t have safari lights, but I do have a clock that I understand is a constant 12V in order to keep the correct time, but the fuse diagram isn’t clear about which fuse is connected to the clock. I imagine the battery is the best place to connect constant and ground wiring, but I’m unsure about making that run. Would you use 16 gauge stranded wire? I’ll see if I can figure out those wago connectors - they seem really expensive. For the three amigos wiring I used waterproof butt splice heat shrink connectors, but I guess the wagos must be much better. I’m decent with soldering from working on guitars a bit, but this is different and I’m pretty oblivious. I’m just wondering if there’s anything else I can use for a ground connection that’s near the passenger fuse box, and, if I can figure out which fuse is used for the clock (assuming that’s 12V - I’d have to measure to know for sure).

Thanks again. I’ve got a bit closer to this now and if it comes down to it, I guess I’ll run wire through the bulkhead (under steering column I’m guessing?) through the tubing to the battery and attach them using ring terminals if I can find any big enough or there’s somewhere convenient on the battery for these purposes.