ECU communication

Over the last couple of weeks, my truck (4.0, 6cyl) cut off a few times, seemingly at random with the only commonality being I was on the brake at the time. The first time while shifting from D to R, once the other way around, and once while slowing to turn into my development. No codes pulled by my cheap little reader and, since it was due for inspection, I took it in and explained the issue to the shop.

They said that the ECU is not communicating with the speed sensor and, while they know what the issue is, they cannot fix it and it needs to go to a dealer for a re-flash.

While driving home from the shop (about 4 miles through town) it died at least 8-10 times. Fortunately, it started right back up and I was able to get it home. I tried a "reset" by disconnecting the battery for a few hours but no change, i.e. it died while backing out of my driveway for the test drive.

So... is there a solution I can try OTHER than submitting to the dealership?

Edit: Speedo and tach are working fine...

 

Is the ABS light on?

 

If it's dieing at a stop and/or low speeds the first thing I would do is clean the throttle body, disconnect the battery for a few min, reconnect, turn the key on for a few seconds, start it, and allow it to idle up to operating temp to relearn the idle.

If your getting a P0500 that's a separate issue from the stalling.

 

No, but the 4WD (both Hi and Lo) lights were flashing.

Throttle body was cleaned just last year and it wasn't in bad shape when I did it. I disconnected the battery for several hours this afternoon and let it idle for about 5 minutes before attempting to test drive it...

Just tried another code reader and it pulled DTC C1241 Low battery, positive voltage?

 

I'd suspect a bad ground then.
Check ground point EE on the back of the passenger cyliner head.

 

If you have freeze frame data (the snow flake) try to see if voltage is stored. I usually look at alternators and batteries when I see c1241, but checking grounds and circuits is always a good idea. Even physically inspecting the master cylinder ECU connector for corrosion.

I've changed ABS ECU's due to C1421, but hopefully yours doesn't come to that.

 

The 4wd lights flashing at the same time as the other problems happening is what's leading me to believe theres a bad ground.

 

Okay, thanks for the leads! I will try to check that stuff in AM, but I really suck at electrical...

 

Cleaned that one, the one by the PS fluid, and the one connected to the negative battery terminal. Went to start it and got nothing but clicks...

Also noticed this just hanging out and did not see any obvious place it should hook up/into -



sigh...

 

Battery is likely pooched, that will cause issues. Will it start with a boost?

That thing hanging is your beeper for the remote fob. You can honestly just zip tie to any point and it will be fine.

 

Check your main block ground from the battery to the engine block.
If that's good and the battery terminals are good have your battery tested.

 

Haven't tried that yet.

Well, that's one "problem" solved!

 

UPDATE: Ended up having the truck towed to the dealership. They had it for a day and a half and I was sick last night thinking about how much this was going to cost me. By noon today, I still had heard nothing. Texted my tech and he said they had not been able to replicate the issue. I was pissed! Not at them but at the truck! He said another tech had it out for a drive and he'd touch base as soon as that tech returned. An hour later, he calls and says they drove it a total of 62 miles, in town and out, and it didn't not do so much as hiccup. He noted that all the electricals looked good (specifically mentioned the ground wires, so thanks for that TWF friends! ). He said that he noticed one of my keys was an aftermarket. I said the PO only had the one, so I had a spare made. He said he thinks that that specific key stopped communicating with the ECU, possibly just due to a low battery, and wants me to drive with both keys in the truck for a week or so and then get back to him, either way. Said he is curious to know now...

Best part of all of this is that he isn't charging me, so super happy at this point!

I appreciate all the suggestions and help!

 

Update to the update!

After two weeks, the truck started cutting out AGAIN! Made an appt. at the dealership to have a new key made. Was going to drive over the evening before and leave it for the next day. Went to start it and... nothing. Battery was completely dead and wouldn't take a charge. Went to disconnect the clamps on the terminals and about 1/2 of the negative clamp fell off as I loosened it. There was a hairline crack that none of us noticed. I don't know for sure if that was the issue but, one new battery and one new clamp later, I drove it for several short errands today and it didn't cut out. We'll see how the rest of the week goes...