Tundra 5.7 150A Alternator….Ugggh

My man card is renewed for yet another year!

After 190,000 miles, I decided to preventatively change the alternator on my Tundra. The Denso’s are known for being perfectly balanced and lasting a long time, but did not want to risk another winter. Mine was lightly howling a teeny bit when very cold, and definitely had rough bearings. I will pull the old Denso alternator apart and check the brushes, and report back. My last Denso (3.4 Tacoma) lasted well over 200K. I will rebuild this one over the winter.

The Tundra 5.7 alternator swap is every bit the nightmare job everyone says it is. It took every 14mm wrench and socket I could dig up in both ⅜ and ¼. Many extensions, pry bars, flashlights, and ratchets (not pictured is the ⅜ torque wrench). About 5 hours.



The dumbest THREE parts are: 1)The blind 14mm bolts on the power steering pump, necessary to remove the PS pump to remove the alternator...accessed through the PS pulley from above. 2) the two 14mm bolts on the bottom of the alternator, directly above the frame member, and tucked in nicely behind the transmission cooler hard lines, and 3) removing the alternator between the frame, shock tower, and lines and wires for whatever is under the front right fender forward of the wheel well. Those three steps alone took about half the 5 hours.

I suspect they decided to mount the alternator down there exactly because of the Denso reliability reputation, but it should get some kind of award for being definitely one of the hardest “easy” jobs on any vehicle...ever.

Behold - I give you the only picture on the internet of the orientation needed to get the alternator out above the frame.



I put in a DB Electrical 150A AND0507 from Amazon ($200). It is listed as ‘new’ and definitely has a new shaft and bearings, but maybe a reclaimed case - it spins very smoothly and pumps out the amps.

I am not a big fan of paying monster repair bills at the Stealership, but this is a job I likely wont ever tackle again.

 

I have not done this job but would bet it's at most equal to the PITA of the 4.8 BMW X5 water cooled alternator job.

That is one reason I'm glad to no longer have that SUV.

 

A watercooled alternator job (I had no idea that existed prior to owning a BMW) is the very reason I no longer own my BMW. I wish i had replaced it when i rebuilt my cooling system back then, but of course it WAITS 250 miles after I finish that job to fail.

I went out and looked at my truck; No chance Ill tackle that job and Im moderately handy. Good for you.

 

I wonder what the dealer cost is to do the work?

 

i am not looking forward to replacing mine. it was hard enough getting in there when i replaced all the power cable as part of the big 4 upgrade i did earlier this year. once i saw where it was, total wtf when i tried to think about getting it out. not in a hurry though, i'm just replacing for more power not because of failure.

 

Good to know. Thanks for the write up. I only at 85K so hopefully this is still way below the horizon. The stupidest repair I've done was the valve cover gaskets on wife's Rx330 on the rear bank against the firewall. Got the plugs while I was there. Finished that one up in about 15 hours total and was shaking my head having to pull off the, wipers cowl, and 2 bolts that took 30 mins each to remove or install. One of them didn't get reinstalled as it was on a support that had 2 other bolts keeping it secured. I think they lower the engine at the dealership.

 

Been there done that..Spent super bowl sunday replacing my alternator because i needed my truck for work the next morning. That PS pump bolts were a Pain the fucking ass to line up.

 

Sometimes I want to find the engineers who make some of these messed up designs and kick them in the balls. I’ve never done extensive work on a transverse engine until I started the timing belt job on my Camry last week.
The FSM says to jack up the engine on that side but screw that. I can’t imagine getting in there through the wheel well to turn the crank 100 times or getting the oil pan back on without hitting something and screwing up the bead of RTV.
Friend of mine who worked as a tech at Toyota for 5 years says they drop the front sub member for jobs like that. I was lucky I had a friends engine hoist in my garage. Yeah it was a bitch to pull the engine/ trans combo but I really wouldn’t want to do it any other way. I’d do the same if I had to do it again.

End threadjack. Sorry op. Good tech info. I am a huge fan of OEM denso alternators. You can probably get new brushes and a voltage regulator from the dealer for less than $200. I’d rebuild it just like you.

 

Just replaced my alternator on my 2015 Tundra 5.7, for the second time.
The placement of this alternator is PERFECT .... for getting mud and dirty water in it.
I'm now scouring the forums to see if anyone has found a way to relocate the alternator, or has built some type of shroud or shield for it to try and protect it a little more.
(Btw, both times I accessed it with a combination of going through the wheel well, and from below ..drop the skid plate and sway bar).

 

The more I read, the more I want to start working on developing callouses on my knuckles because there
must be blood involved too! Fingers crossed I'm a couple years away from this yet.

 

Beats having to remove the intake manifold on my 2000.

 

I heard 4x4 is harder than 2x4 models, I have a 2x model 2008, and did it once at 210k miles (autozone) and again at 230k Toyota denso from the local stealership

 

Replacing the starter on these trucks is also an adventure is several hours wasted... Just trying to figure out how to take out bolts that are mounted in reverse. Anyways not a fun job at all.

 

In the process of doing this job right now. its the hardest easiest job on a Tundra I'm in it at least 12+ hours I broke the front lower alt bolt should be able to make a notch and screw it out with a screw driver as the butt end has enough showing to do so. Mine is 4x4 and it is indeed harder with the towing package there is a line that gets in the way Propane Torch PB Blaster are your friends. It took 4-5hours just to get the Power Steering pump out of the way my truck is all original and everything has been in place for 18 years had to tap the pump out with a big screwdriver ratchet with a wiggle head is a must this job gave me an excuse to buy one Mine came out the bottom I did drop the sway park and transmission lines from the bolt above the oil pan. If I was doing again I would just take out the power steering pump that will save time and you don't have to fight with it swinging in the way. I did not have to remove the radiator hose it can be worked around. Now I begin getting it all back together once I screw the bolt out had to get a new bolt from the dealer. It was my fault i tightied too hard instead of loosied and the bolt went pop. I will say this replacing the valve cover gasket was much easier than this.

 

Yes I went the same route.
Removed the PS Pump through the wheel well, didn't remove the radiator... it was a little sketchy at points with as much pressure as I had to put on the radiator hoses, I was a bit concerned I might break something, but it held.
Dropping the sway bar and disconnecting the cable anchors was an absolute must.
The PS pump was by far the the most time consuming part.

What else can I note here.
I replaced the alternator with a High Output 250A JS alternator (3000watt).... if you're going to replace it, why not go ahead and get an upgrade while you're at it. Especially with my Platinum that has all these extra electrical devices, and if you want to add stuff like a winch or high output lights, it's a good idea.

Here's something else... I'll post some links for some tools that I purchased for the alternator swap.

MIXPOWER 25 Piece Torx Bit and Socket Set, 13 Star Bits (T8- T60) & 12 E-Torx Sockets (E4-E22)

$21 MIXPOWER 25 Piece Torx Bit and Socket Set, 13 Star Bits (T8- T60) & 12 E-Torx Sockets (E4-E22), Professional Grade Auto & Motorcycle Mechanic Set

https://www.amazon.com/dp/B08ZJ56Z9W?th=1

DURATECH Offset Box Wrench Set, Metric, 9-Piece, 6-23mm, 75-Degree

$30 DURATECH Offset Box Wrench Set, Metric, 9-Piece, 6-23mm, 75-Degree, CR-V Steel, Organized in Rolling Pouch

https://www.amazon.com/dp/B08FB12R2J?th=1

SUNEX TOOLS 26491 1/2-Inch Drive 6-mm Hex Impact Socket

$14 SUNEX TOOLS 26491 1/2" Drive 6-mm Hex Impact Socket

https://www.amazon.com/dp/B002YKO8DE

 

Hey I'm thinking of upgrading my alternator as well. Was looking into the JS Alternator or a Mechman alternator. I have an audio system, snow plow and lights so I need anything that can help avoid that. My electrical system go dim all around when running the plow in these winter storms. My question to you is how is your alternator upgrade working out for you?

 

My alternator went out @220k miles I did some research on the job that i wasn’t fond of and did find a garage that did the job with a Denso 150 amp alternator installed for $700 sometimes you are just better off paying someone

 

Hey sorry about the lag time in response, I get a bajillion emails a day and notifications from this forum get lost in the sauce sometimes.
Only about a month late lol.
To answer your question: it's been running fantastic, I have a ton of electronics on my truck and it runs everything effortlessly... only time I get voltage drop is when I'm doing a hard pull with my 9500lbs winch, it slams the system for half a second and then revs the truck up a little and no problem. That's pretty normal I think. I have the two battery system, added an extra one in the bed up against the cab, with 1/0 OFC cable running positive and grounded to the frame through the bed mounting bolt -- I recently bought another run of 20' 1/0 to do an actual ground line back rather than using the frame, it's supposed to help a little with the voltage drop, but probably overkill.

I will say this though, I killed my first one by running through some deeper water, Idk WHY toyota thought it was a good idea to mount the alternator at the bottom of the engine right near the wheel well instead of more up towards the top like a lot of vehicles do.
It def didn't help that my plastics are all jacked up from my aftermarket bumper and 34" MT tires... I just did a 3D scan of the wheel well last week and plan on designing and 3D printing my own splash guards.
Also scanned the alternator itself thinking i might design some sort of partial case around it, but the space is very limited in there so I'm not sure if that idea will work out.
Not so much a flaw on JS's side, that would have corroded out the OEM alternator as well.
Pretty cool though, JS honored their warranty and sent me a new one, I just had to cover the shipping.
Only a couple months later they released their new version, which looks way cooler and has more casing around it, little more protected from water splash damage. Wish I could have gotten one of those but oh well.

I can also copy paste this inventory with notes of my electrical draw devices (organized by chatgpt), you might find it to be of some use:

2015 Toyota Tundra — Electrical Inventory, Load Scenarios & Voltage Drop (v2)
Alternator: JS High Output 250 A • Batteries: 2× truck batteries in parallel (bed battery via ~17 ft 1/0 OFC pos + 17 ft 1/0 OFC ground to engine bay) • Big‑3: upgraded to 1/0 OFC

Inventory — Manufacturer Specs (12 V unless noted)
Lighting

• Ironman Bright Saber 32″ dual‑row light bar (ILBDR002B): 300 W, 20.8 A @12 V
  
  
• Ironman 3″ pods (front, 4×): 40 W each → 160 W (~13.3 A) total
  
  
• SpeedTech Lights Raptor‑X TIR visor strobe (front): ≈ 4.2 A
  
  
• Rear strobe bar: 48 W (~4.0 A)
  

Comms / Electronics

• BTECH GMRS‑50V2: ~12 A typical TX, ~20 A peak @13.8 V
  
  
• ATOTO S8 head unit: no DC input published; ~1–3 A typical (using 2 A)
  
  
• Dash cams (dual): ~3–5 W (≈ 0.25–0.4 A)
  
  
• AHD backup cam: ~2 W (≈ 0.17 A)
  
  
• Valentine One Gen2: 2.8 W typical, 5.2 W max (0.23–0.43 A)
  
  
• Netgear Nighthawk M1 hotspot (MR1100): ~10 W @5 V → ~0.8–1.0 A @12 V incl. conversion
  
  
• weBoost Drive Reach: 1.8 A (≈ 22 W)
  
  
• YoLink hub: ~0.5 W (≈ 0.04 A)
  
  
• Pedal Commander: ≤ 0.1 A (logic‑level)
  

Appliance / Power

• EUHOMY 59Q compressor fridge: ~45 W avg (≈ 3.8 A when running; duty‑cycled)
  
  
• BELTTT 3000 W pure‑sine inverter (BAP3000A): idle ~20–24 W (1.7–2.0 A); at full 3000 W AC ≈ 280 A DC
  

Recovery

• Ironman ~9,500 lb winch: ~74 A light‑load up to ~350 A max at heavy pull
  

Center‑Console Power Hub Branch (new)

• Positive/negative posts inside console (no draw; distribution only)
  
  
• EUGIZMO 12 V 3‑socket + USB hub (rated 200 W): ≤ 200 W across the sockets → ≤ ~16.7 A @12 V (USB ports add a few amps at 5 V but are part of that budget if powered via the hub’s plug). Use your toggle to hard‑isolate when not needed.
  
  
• Small AC inverter on hub (usually OFF): typical 120–150 W class → ~12–15 A @12 V at full tilt; idle draw often ~0.3–0.6 A if switched on with no load.
  
  
• Typical loads plugged into hub: hotspot (~0.9 A), YoLink (~0.04 A), weBoost (1.8 A), 2× phone fast chargers (usually ~15–20 W each depending on charger → ~2.5–3.5 A combined @12 V accounting for conversion).
  
  
• ECO‑WORTHY 300 A Hall battery monitor: display/control current is very low (plan ≤ 0.1 A).
  
  
• Occasional trickle items: mini headlamp charger, NOCO pack, etc. — generally < 1 A combined unless the NOCO is fast‑charging.
  

Scenario Totals (12–14.2 V bus)
A) Night‑Run (everything on except winch; inverter at idle)

• Bar (20.8 A) + Pods (13.3 A) + Front strobe (4.2 A) + Rear strobe (4.0 A)
  
  
• HU (2.0 A) + Dash + Backup cams (0.52 A) + V1 (0.43 A)
  
  
• MR1100 (1.0 A) + weBoost (1.8 A) + YoLink (0.04 A) + Fridge (3.8 A) + Inverter idle (2.0 A)
  

Total: ≈ 53.9 A (~700 W) while fridge is running (minus ~3.8 A when it cycles off). GMRS TX burst adds ~12 A typical (up to ~20 A peak @13.8 V).

Night‑Run + phones fast‑charging (center‑console hub): add ~3–4 A (≈ 40–50 W) if both iPhone 13 Pro Max units are on 18–20 W chargers; add another ~0.5–1 A if the small hub‑inverter is ON but idle.
→ Adjusted total: ~57–59 A (~740–760 W).

B) Absolute Max (theoretical ceiling)

• Night‑Run + GMRS peak (20 A) + Winch max (350 A) + Inverter full (≈ 280 A)
  

Total: ≈ 704 A (~8.5 kW) → purely theoretical; you would never run winch + 3 kW inverter + full lighting simultaneously.

Alternator Headroom — JS 250 A HO

• Cruise output: up to 250 A; Night‑Run (~62 A) leaves ~188 A margin.
  
  
• Idle output: ~150–180 A; still ample for Night‑Run.
  
  
• High‑draw events: Winch or inverter under load exceed alternator output; batteries supply difference.
  

Voltage Drop on the Bed Battery Runs (1/0 OFC, 17 ft pos + 17 ft ground → 34 ft round‑trip)

• 1/0 OFC: ~0.00334 Ω total → 350 A = 1.17 V drop (~9% at 12.6 V; ~410 W heat)
  
  
• Dual 1/0 in parallel: ~0.00167 Ω → 350 A = 0.58 V drop (~4% at 12.6 V; ~204 W heat)
  

Wiring, Fusing & Layout Recommendations

1. Winch circuit (front battery only)
   

• Cable: Short, straight 2/0 OFC minimum (3/0 preferred if runs exceed ~5–6 ft). Keep both pos and ground to battery (or to a heavy frame stud + dedicated frame‑to‑battery 2/0 bond).
  
  
• Protection: Many winch makers advise no fuse due to inrush. If you choose protection, use a slow‑blow 400–500 A class device or a high‑amp manual disconnect/contactor mounted near the battery.
  
  
• Grounding: Add redundant grounds: battery‑to‑frame 2/0, battery‑to‑engine 2/0; abrade/prime‑free metal for lugs, then coat.
  

1. Inverter branch (ideally mounted by the bed battery)
   

• Fuse: 300 A class‑T or ANL within 7″ of the battery.
  
  
• Cable: 2/0 OFC for ≤ 2000 W; 3/0 OFC recommended approaching 3000 W. Keep DC leads < 5–6 ft round‑trip if possible.
  
  
• Chassis bonding: Add a bed‑to‑frame 2/0 jumper near the inverter.
  

1. Lighting / Accessories (use a front 12‑pos fused bus)
   

• Bar (20.8 A): 40 A fuse, 10 AWG run.
  
  
• Pods (13.3 A total): 25–30 A fuse shared or 15 A per pair, 12 AWG.
  
  
• Front visor (4.2 A): 10 A fuse, 16–14 AWG.
  
  
• Rear strobe (4.0 A): 10 A fuse, 16–14 AWG.
  
  
• GMRS: 20 A fuse at battery, 12–14 AWG.
  
  
• Fridge (~3.8 A avg, ~8–10 A start): 15 A fuse, 12–10 AWG to bed power panel.
  
  
• weBoost (1.8 A), MR1100 (~1 A), V1 (≤0.5 A), cams (≤0.5 A): 5–10 A fused branch each, 18–16 AWG is fine.
  

1. Center‑console hub branch (new)
   

• Feed: Your 12 AWG feed is appropriate for the hub’s ≤ 200 W (≤ 16.7 A) rating.
  
  
• Fuse: 20–25 A at the bus bar (stay ≤ 25 A for 12 AWG unless the run is extremely short and well‑protected). Place a toggle in‑console (already installed) to hard‑isolate.
  
  
• Loads: Phones fast‑charging add ~3–4 A; small hub‑inverter idle adds ~0.5 A (full 120–150 W load would be 10–15 A and should be short‑duration on 12 AWG).
  
  
• Ground: Keep a short 12 AWG ground from the console post to a low‑impedance chassis bond; ensure the main battery‑to‑body 1/0 is present (Big‑3 handled).
  

Quick Planning Summary

• Night‑Run: ~62 A (~800 W) — well within alternator.
  
  
• Winch event: up to ~350 A; keep other big loads off.
  
  
• Inverter heavy use: short, fat cables, fuse appropriately, avoid long runs from front battery.
  

 

No worries I understand how it is lol
Thank you for getting back with your response. It truly helped me decide with going forward with the alternator upgrade.