Here is the in-depth write-up that I hope can serve as a how-to for OM617-swapping 96-04 Tacomas/4Runners (and T100's).
I picked up this $600 1997 4Runner 5VZ/A340 4x4 (rear e-locker) with roughly 250k miles and it was SHOT! Completely rusted out even though the body doesn't show it. Destroyed interior. Radiator blew up and mixed trans fluid with coolant to make a milkshake in the trans. Now I haven't read a single report of anyone flushing their trans and successfully driving it after that. Even the ones done under warranty at the dealership with the power flush had trans failure shortly after. Keep an eye on your radiator if you've got an automatic! The PO claims he noticed it right away and had it towed home where I picked it up. I flush the trans, added a new radiator, and put another 30k on the 5VZ! I daily drove it to work, used it to tow the mower trailer around, and even drove it 3 hours into Iowa with the trailer to get a band saw. Did a fair amount of wheeling with it, too, enjoying the rear locker. Eventually, it started losing coolant, so the 5VZ got yanked and sold.
The plan for this has always been for R&D. The only money I have into this rig is the new radiator and mounting the free tires someone was throwing away. Sold the 5VZ to cover the purchase. Can't beat that! I'm currently swapping in an OM617. I'll be using the 4Reigner to test trails I'm cutting in our pasture, as well as haul the tree cutting equipment around. Since the frame is already falling apart, I don't expect to keep this around much longer. I had originally planned to do a TDI swap after the 617, but have since decided not to worry about making TDI adapters for the Toyota Automatics, as the torque converter pilot stub would require turning down, and that is probably too much effort for most people. Once the frame folds in half, I'll pull the 617 back out to go into something long-term, and I'll save the rear axle and trans.
Gauges Part 2
The critical gauges I always run in anything are:
-Oil Pressure (your engine's blood)
-Water Temp (to prevent blown headgaskets)
-Pyrometer (to prevent melted pistons)
-Boost (to prevent blown headgaskets)
-Tachometer (used for setting idle and getting good MPG by finding target RPM)
If I have an automatic, I also run a Trans Temp (see the Gauges Part 1 post).
These 96-04 have terrible gauge clusters. They don't even have a volt meter for crying out loud. I don't know what happened to SR5's having all the fixings, but these don't. In my opinion, every vehicle should have all of these gauges.
I decided to run Glow Shift gauges for this project, as AutoMeter quality has gone down the toilet, while their prices have sky-rocketed. I opted for the White Elite 10-color series. GS has so many more perks over AM. AM wants $10 for an LED bulb to change the backlight. GS has every color pre-installed, to change with a click of a button. AM has outdated wiring while GS includes a daisy-chain feature. GS also has many more features:
-Records your Peak value for you to reference at any time by pressing the Set button
-Offers flashing and beeping alarms for Hi and Low values that you set
-Can output a signal for said warnings, for you to run things like a larger warning light or trigger an engine shut-off solenoid, etc.
My only gripes about these GS gauges are that the White 10-Color don't have a Water Temp gauge, which is asinine to me since that is a basic, critical, fundamental gauge. And, they don't have backup batteries to remember your settings - so if you disconnect or drain the battery, you have to reprogram all of them. Not a huge deal, as it takes less than 2-3 minutes to do. People also complain about the brightness, and I tend to agree. They dim when your lights are turned on (if you connect the appropriate wire), but I find the White light to still be too bright at night. I wanted white to match my new gauge cluster backlight. I've found myself switching to Green at night. I will also say that the 2 color changing modes (1 blinks from 1 color to the next, the other slowly fades from 1 to the next) are idiotic and just add extra unnecessary clicks when changing between White & Green. I realize that's bold, but seriously, running a bright gauge that changes colors constantly is a hazard to the driver.
Lastly, none of their gauges are mechanical. Mechanical fits so well with Doomsday, and I hate sensors, but the benefits outweigh the cons in my opinion for this build.
Here are the 4 gauges daisy-chained together, so I only had to hook 1 wire up instead of 4, for each function. SOOOO much cleaner than an AM setup. I put them in a pod to make mounting simple for this cheap/quick build. They have every mount style you could imagine, and at great prices. I actually ditched this solid mount for an articulating pod setup, so I could individually aim each gauge towards my line of sight.
I reluctantly ended up using the Toyota Water Temp gauge, but it's working well, and I know the values after finding them in a Toyota manual, so it's not just a needle pointed at an arbitrary point.
Here, I've got the hood removed while I'm waiting for intercooler connections to show up. I wanted to test the IC in a best-case scenario, where it's getting full possible flow. If it doesn't work here, I'll know it's definitely too small to go under the hood. As you can tell by my gauges while cruising, it works excellently.
I ultimately tucked the IC under the hood, and it still works well. I plan to eventually add either a hood scoop or a louver. Still undecided, as the air filter partially rests directly underneath the fins of the, and I can't have water pouring down into the filter. That's still a work-in-progress. For now, the EGT's can get up to 1200°F on a long, steep climb with cruise on. I can also peg 1300 if I'm trying to pass someone above 65mph. These engines were designed to run at a constant 1250°, but as I mentioned before, excessive heat just kills longevity. With the stock 30.6" tires and 4.30's, it will cruise at 600° in 3rd and 800-1000 in OD. This is another indication that I'm undergeared.
There are actually 2 water temp sensors. The spade terminal unit is for the gauge; the weather connector is for the ECU. I mounted the ECU sensor in the tstat housing, as it's a perfect location for the wiring harness, and the thread is conveniently close to tap out.
The ECU sensor serves several functions, still, in this swap. In stock configuration, it should kick off the AC if the temp gets too high. Shift points are likely affected by it, too.
The gauge sensor got adapted to the head fitting behind the injection pump, with an adapter from GS. I had to extend the wiring harness wire to reach this location, but it reads the temp in the middle of the head, and is easily accessible.
I ran all of the wires for the aftermarket gauges thru the factory grommet, to make things look clean/factory, as well as protect them, nicely.
The tachometer is a can of worms... I will say this clearly right here:
I DO NOT ENDORSE DAKOTA DIGITAL.
I had initially been using the DSL1 in my swaps. It worked just fine. Then, DD obsoleted it in favor of the SGI8. I called when the DSL1 was listed as NLA, and the guy on the phone told me to start using the SGI8. I found a good deal on them, and bought a bundle of them. Finally ran out of DSL1's on my last customer's build, and had to use my first SGI8. The signal worked fine until 3000 RPM, then the tach would die. I called tech support for troubleshooting, and this is where my support for Dakota Digital died. In their never-ending quest to consolidate parts, they've taken a $70 module and replaced it with a $110 module with bluetooth and all this jazz that none of us need, want, or will ever use. The guy on the phone immediately scoffs at me for asking for help with an SGI8 module, acting like it's been obsolete for 10 years. He claims he can't even pull up any documentation for it. We get into the troubleshooting, and he tells me this is not going to work at all - it's not for diesel tachs. Well that's pretty damned funny... it's called the "UNIVERSAL TACH INTERFACE" - says it right on the module. I informed him that Dakota Digital told me to start using the SGI8. He told me "no we didn't". It was at this point that I was ready to slam the phone. I gritted my teeth and tried to get some technical troubleshooting points. All he could offer was "just push buttons and try different things".
THANKS FOR NOTHING, DAKOTA DIGITAL! I WILL NEVER BUY ANOTHER PRODUCT FROM YOU!
I ended up figuring out how to calibrate the SGI8, and it works even better than the DSL1 ever did. Too bad they had to obsolete them. Honestly, the bluetooth adjustments would be great, as I have this thing hidden way up inside the dash, and adjusting was a PITA. A correction factor of 966 with an IN of 6? and OUT of 10? (of course I lost my pictures of the IN/OUT settings... comment if you need them and I'll dig the module out and read them again) got the tach working perfectly using the AD230 alternator output. It is buttery smooth.
Hooking it up is a breeze - you give it 12v with the key on RUN, ground it, send the AD alternator's "P" to the Signal-In, and the Normal Output goes to your gauge cluster tach input. I piggy-backed the Glow Shift gauge power to eliminate a splice/butt joint connector. I used a simple add-a-fuse to pull my 12V from the fuse panel.
Some tape-on velcro makes mounting and removing simple.
If the battery is disconnected, it still retains its settings. I wish the GS gauges did this. I could not imagine pulling the dash to reprogram the tach module every time I disconnect the battery.
As for connecting the rest of the gauge wires goes, it was extremely simple and convenient with the existing 4Runner fuse panel. The tach module and gauges get 12V in RUN. The gauges need constant 12V to keep their memory (this could potentially drain your battery over long periods of time). And my OM617 Wiring Harness needs power with key on ACC, to shut the engine off.
The gauges also need 12v when the lights are turned on, to activate the dimming feature. This was easily done by removing the plug from the dimmer switch, removing the hot wire going in, and crimping a new spade terminal over 2 wires. This makes it look factory (you know, cuz people are totally removing your dash at car shows to look at your wiring connections 🙃) and it makes for a strong, solid connection.