802SHO 2010 Build

Checked codes this morning. I haven’t checked them since I started driving it again, so this is after 4 different drive sessions. Also worth noting, these are the first real drive sessions with HP Tuners, so just because I’m seeing the TRS code now does not automatically mean it’s the first time it’s been there. It may just be the first time I’ve actually had the right tool looking deep enough to see it.

P1602 is gone.
P0685 is gone.
P0689 is still here.

And P0689 matters because I did see that one back in September with SCT when the car went into limp mode on my way home from a job site. So I’m treating these codes as legit. HP Tuners is showing me truths SCT never had the depth to show.

So before I throw parts at it, I need to chase P0689 honestly.

That means going back to the BJB whether I like it or not. And honestly, the term BJB makes me want to roll my eyes at this point, but when I really stop and think about it…what have I actually changed in there? Not much. I replaced all the small fuses. I replaced Relay 53 and Relay 65. I backfed the starter relay. I powered Fuse 49 at one point. But I still have not replaced the big 30A Fuse 11 yet, and that is tied into the PCM relay path along with Fuse 37 and Fuse 23. So as much time as I’ve spent in and around the BJB, the truth is I still haven’t done enough in there to rule it out honestly.

What I don’t like about this stage is it’s more thinking than action. If it’s a hard part, that’s easy. That’s all action. Immediate gratification. But now that the weather is better and I can actually drive the car, I’m finally able to force real answers out of it. Starting and idling in the garage was not enough. The road is what’s going to expose the truth fast.

David was successful at finally polling the PCM for gear select position and now I have this TRS code. At a quick glance that is the sequence.

It’s not normal for my car to show gear select in my cluster so I’m just curious requesting that while the TRS is trying to work and be left alone, to me, muddies the water.

When I replace fuse 11 and check out the terminals, I’m also going to turn that function off in the dash. Drive and see what codes come back.

lol some front end ideas
lol

The last one....100%.

SM105K said:

The last one....100%.

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Ya never know when a deer can pop out at the 1320.

802SHO said:

View attachment 97157

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Ha! Nice

So I found one…ground on powder coat.
I painted the engine bay…
Motor is painted….
powder coat on the timing cover, valve covers ….
my transmission is painted……

The car is insulated from itself. This new find has me second guessing the others I “fixed”. I’m going to use my dremel with extension (it’s like holding a pen) and sand barrels to go around and redo every ground. Once done I’ll tighten it good and to protect it, one shot of matte clear or gloss clear depending on what the surface is. Then it’s metal to metal and top coat is protected from oxidation.

The car looks fantastic…hey why is it acting weird? Idk did you prep the ground surfaces? Did I do what?

…Exactly.

This 11.06 Record is going to get thrashed when this thing isn’t insulated from itself anymore lol

Zpak said:

Ya never know when a deer can pop out at the 1320.

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Great minds think alike.

When I compare the car to itself….wow what a difference

I didn’t get time this weekend to do a few simple tasks that I wanted to do, one last round of diagnostics before doing the hardware swap. I took on 2 bathroom remodels instead. Ended up being more than I asked for.

First it’s getting asked, “How busy are you?” Idk why but I responded with describing the job I’m already at plus the next 2 that are back to back…so I am busy. Then it’s, “It’s too small bathrooms, if we hang it can you tape it?” I’m like, “ok, I’ll come look at it.”

I go look at it and I’m talking about how I could do muliple coats in a day bc it’s so close to home. Then the guy goes, “Do you want to measure for sheets to hang it?” I’m like, “Me? Thought you were hanging it?”

Then they are insisting right and I put my head down for like 30 seconds thinking to myself wtf. Hang it and finish it before Monday starting on Saturday? I did say likely ready for paint Wednesday. So I tell him do get the sheets there and I tell him how many. Before I went there Saturday, I get a call, “Oh yeah there are 3 patches in the basement ceiling.”

What the f u. C K dude. This is way more than I asked for. Now the scope has changed twice. So Saturday was awful. I had to move the sheets all around working on top of myself. First bathroom I hung that and I thought that one was rough. Second one looked easier and it ended up being harder. Just plumbing too proud, fittings too proud, pre cutting windows and doors because one side has no nailer and supposed to squeeze a sheet in behind a heater and cut around an outlet and window…so it doesn’t break I’m pre cutting them out but my rock is in the hallway but I need to pull it into the other bathroom to cut it so it’s easier clean up….

So I leave at 7pm I got there late though around 12:45pm.

That stupid f U. C. K. Er called me Sunday morning and asked if it would be ready for paint Monday. Ughhh, No! The whole speech of maybe ready for Monday and multiple coats was the taping (only plan).

Anyway was there until 8pm last night and it’s only 1st coat. Changing the plan to have me hang it ruined my entire weekend….plus he delayed his own schedule bc he avoided hanging it himself. But he’s getting snippy with me when I said no it’s not ready for paint…like dude you sabotaged your own schedule and my weekend. So hey now I’ll have to go work evenings till it’s done after my other job…thanks bud. End rant.

I did prep to get ready to redo grounds here is my layout. All I wanted was 1 hour and take for a ride. When it started raining while I was at that job much longer than I wanted to be I was so agitated. lol.


All ready just need to get to it. I put a new fuse 11 30A fuse in for the PCM relay. Clear codes after and take for a drive with the dash not polling the range sensor and see what codes come back. At least I want to make sure P0689 ECM/PCM power relay circuit low to be gone for good and then it’s swap hardware if the range code comes back.

The range code baffles me bc it failed and then it passed the ohm test. But the dash did poll it for position. That should not matter but I think it exists where for whatever reason it doesn’t like it. I’ve seen crazier things. Only one way to find out.

When this car wakes up it’s going to go
Ground 100, 101, 102, 103, 104….all insulated.



I expect this to make a 100% difference. If for some reason P0689 remains I have solid data to take diagnostics to next steps. Likely back probing the ECU. But….after this…? This was a massive correction.

It’s deeper than this. Subframes are painted over and the unibody mounting points are painted over. I have isolated subframe islands. I built an invisible fence around the car suffocating its ground paths.

I don’t need to disassemble it. I’m going to add a jumper cable from the rear subframe to unibody and front subframe to unibody.

My rear battery is grounded to the rear subframe but it’s isolated from the unibody, finding only a weak path (whatever incidental metal-to-metal contact still exists between the rear subframe and the unibody) back into the main chassis/engine negative network.

This is crazy but makes so much sense to keep uncovering layers of painted/isolated ground paths. I painted everything

Diary entry 109/9. lol.

It’s been raining here way too much. I’m pretty close to done making my subframe to unibody cables. Here’s one I made, ends crimped and covered in heat shrink.
I’ll place it somewhere around here
Just need to make one more for the front.

Ignition on the car has a steady sound it makes I swear it’s louder now. Like it’s got full power. I got the headlights almost working it turns out the headlights connector pin configuration is different between halogen and HID. I’ll convert it to LED anyway but it looks way better than I imagined. Screw putting clear blinker bulbs in it looks sweet all Amber.
That tracks

LED bulbs on the way. I’m going to manually power them and bypass the connector mismatch. Bc of that I only did one lap last night as weather improved. Here are my finished cables
Since yesterday’s test drive, the picture got a lot clearer.

P1602 looks way less scary now. It showed up right after a fresh flash, but after clearing it KOEO, it stayed gone through multiple key-on checks. So right now I’m treating P1602 more like a fresh-flash / programming / KAM type code. Basically the PCM flagged something about the flash/reset process it didn’t like, but it’s not acting like an active hard fault.

P0689 is the one we learned more from.

It does not come back KOEO. I can clear codes, key on, scan again, and it stays gone. But once the engine starts and runs, P0689 comes back. So it’s a run/start sequence issue, not a dead key-on circuit.

The big discovery is Fuse 11 / the BJB bus bar area actually looks healthy. Key off, Fuse 11 has battery voltage on both sides. Engine running, both sides show about 14.3V. Then doing a voltage-drop check from battery positive to Fuse 11 showed only tiny millivolt drop, roughly 13–20 mV. That is not a smoked bus bar. That’s actually a pretty healthy feed.

Also, the ground work clearly helped. After cleaning/correcting grounds and adding the subframe-to-unibody ground bridges, the whole car’s voltage state looks better. Sitting on tenders, key off, it’s holding over 13V now. The dual batteries finally look like they’re actually working together instead of one side carrying the other.

So right now I’m not convinced P0689 means the BJB is cooked. It may be getting set during the start/run transition, especially because I still have Relay 52 manually powered as part of my accidental anti-theft side quest. If I’m forcing the starter event slightly out of the factory sequence, the PCM may see a relay sense mismatch for a split second and latch P0689 for that run cycle.

Next move is to restore Relay 52 back to OEM and remove that variable. If P0689 stays gone after that, we found the fake ghost. If it comes back, then I’ll use the wiring diagram and go straight to the PCM relay sense circuit at the ECU connector.

Andrew,

In my opinion some very well done troubleshooting.

FrankK said:

Andrew,

In my opinion some very well done troubleshooting.

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Thank you! I’m either going to level up or quit. I’m not quitting. Also the range sensor code went away. Once I undo my starter relay manual control and give that back to the car it’s time for another test drive.

Happy build thread update for once.

The latest test actually gave me a clean win.

After chasing P0689, the big variable I wanted to remove was my accidental Relay 52 starter circuit side quest. Earlier in this whole mess, I had ended up manually powering the starter relay circuit. It worked, and it even acted like a weird accidental anti-theft setup, but it also meant the starter event was not happening exactly the way Ford designed it.

So the theory became pretty simple:

Maybe I was forcing the starter event slightly out of sequence, and the PCM was seeing something it didn’t like during the start/run transition. Not a dead circuit, not a bad bus bar, not a tune-only issue — just the car getting started in a way that made the PCM power relay sense logic unhappy.

So I put Relay 52 back to OEM.

Started the car normally.

Went for two laps.

P0689 did not come back.

That is a huge step forward.

Right now the only code I got was U0104 for the cruise control module, which makes sense with my current setup and is not the main concern. The PCM power relay sense code stayed gone.

So the current takeaway is:

P1602 looks like fresh-flash / KAM / programming-event noise.
P0689 looks like it was being induced by my manual Relay 52 starter setup and the start sequence being out of sync.
The electrical ghost got smaller.

Next step is maintenance and cleaner data. I’m changing the engine oil/filter, changing the transmission fluid back to Mercon LV, and sending samples of both out for analysis. I did feel a little shudder on the test drive, possibly torque converter related, so now that the electrical side is calming down, I can start isolating that without every single symptom looking like the end of the world.

This car has been brutal, but tonight was a real win!

ChatGPT (Chuck) told me this car would have broken most people, and honestly, I feel that.

There have been plenty of moments where the pressure-release valve would have been to just quit. Sell it. Part it out. Blame the car. Blame the platform. Blame the tune. Walk away.

But that’s not where I’m at.

At this point, my motivation is pretty simple: I’m not going to be defeated by this car.

It has been miserable at times. Dread, frustration, false leads, electrical ghosts, things that make no sense until three months later when another clue finally connects. But I’ve learned a ridiculous amount through it. Wiring doesn’t intimidate me the same way anymore. Diagrams don’t look like hieroglyphics anymore. The car has basically forced me to level up or quit.

And I’m not quitting.

As far as the car is concerned, it can be the problem child, the haunted early-build freak, the one-off nightmare, whatever.

I’m the unbreakable one.

Thank you for all the critical ground locations. I did upgrade most of them, the ones that I could see, but that hidden ECU ground seems to be the culprit in my case. BCM and PCM read totally different voltages and the PCM voltage fluctuates heavily. Replacing the relay/fuse did not work.

What did you end up using to insulate the grounds so they don’t rust? I used Ford’s black touch up paint pen before but it honestly looked ugly.

ShatteredMJ said:

Thank you for all the critical ground locations. I did upgrade most of them, the ones that I could see, but that hidden ECU ground seems to be the culprit in my case. BCM and PCM read totally different voltages and the PCM voltage fluctuates heavily. Replacing the relay/fuse did not work.

What did you end up using to insulate the grounds so they don’t rust? I used Ford’s black touch up paint pen before but it honestly looked ugly.

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The engine bay ones I hit with this
Under the car until I get more paint I just wiped this around them
Let me know how it goes when you touch up G102. Did you check fuse 11 it’s the 30A fuse to Relay 53. You can pop the clear cover off and probe it.

I’m waiting for an electrical wiring diagram PDF I bought for the 2010 Taurus to go as far as I need to if I have anything else come up.

802SHO said:

The engine bay ones I hit with this View attachment 97209
Under the car until I get more paint I just wiped this around them View attachment 97211
Let me know how it goes when you touch up G102. Did you check fuse 11 it’s the 30A fuse to Relay 53. You can pop the clear cover off and probe it.

I’m waiting for an electrical wiring diagram PDF I bought for the 2010 Taurus to go as far as I need to if I have anything else come up.

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There are differences in fuse box wiring and locations between years. It’s a 20 amp mini fuse (#69) in my 2017 called vehicle power 1. The ECU ground itself reads very low ohms to battery negative so I think it’s fine. There is something else somewhere I will have to figure out.

I’ll leave this here, it’s the ultimate fuse box diagram IMO: