alx

you have a faulty ecu harness... or a faulty ecu.

i am leaning towards faulty ecu harness.

i would start by taking truck to dealership and paying for one hour to verify all grounds and harness fusable links. if those check out i would verify all connectors around the ecu and visually inspect all harness lengths i can get my eyes on

eric_in_sd

Given that he's found corroded connectors, it seems obvious to me.
A little hard to imagine the ecu being marginal like that. Seems like it would either be on or off.

bhuter24

I have taken the truck to the dealership twice and they kept giving me same answer, "They are not sure what is wrong, first they told me it was spark plug coils and then they said it is faulty crank position sensor.

Here is my another question, if i use the scanner to reset the codes the vehicle preforms fine for about an hours or sometimes a day. the very first code that comes back almost instantly is Outside Ambient Temp Sensor, should I tackle this first, This code is always there but the other codes are hit and miss.

eric_in_sd

I think you have to be specific about what you need done. This would not be an estimate, but rather a diagnosis and repair procedure.
In my experience the limp mode results in the ECU vomiting up an assortment of other codes. The rough idle and stuff sounds like limp mode, in which the fuel system goes open loop. That is, it stops using feedback from the exhaust to adjust the air/fuel mixture. It runs the motor lean to protect the cats.. Your MBII will tell you whether it has gone open loop, but not explicitly. You have to look at the S1 oxy sensor output. I forget which direction the lambda goes, but I think it's values greater than 1, with 1 being the target. When it goes open loop, other motor diagnostic stuff pops up, which the system figures it's better to not ignore and reports anyway.
Now, that doesn't mean that your other errors are secondary. I'm just saying, tackle first things first. Overhaul those connectors. Get yourself three wash bottles. Fill the first with DI ("distilled") water. Vinegar and a baking soda solution (doesn't have to be strong; like a teaspoon per quart) in the other two. Flush them out with vinegar, then baking soda, then rinse with DI water. Blow them out with compressed air, then reconnect. You don't have to use much of any of the three liquids. Possibly leave the vinegar sitting in the connector for a few minutes.
The corrosion may have gotten deeper in, like into the crimps between the wires and the spades and lugs. But, again, first things first.
The connector to the temp sensor is down low, near the front, right? Exposed to the road salt?

bhuter24

So are you referring to any electric connector that I can see or open flush them or are you talking about specific ones?

Yes the outside Ambient Temp is right at the front on front bumper exposed to road derbies.

eric_in_sd

First things first. The connectors that the ECU is telling you are causing trouble.

I would never put on a hat I found in the road, so it would not surprise me that the connector had trouble.

bhuter24

I think I know the answer but still wanted to confirm, Can I swap the ECU with my other vehicle and test it or it's not possible since it would require reprogramming the ECU by the dealer and they won't reprogram a used one?

machadosl

The ECU swap is not possible, it requires the recognition os the EZS key module and, in case you do that, there is a small chance to block the engine start of both cars.
One thing I am having problems here in Brazil is with the poor quality of the fuel, it gets old faster leading to these misfire problems in my car. I am going to replace the spark plugs that are on it for lazer iridium to see if this can solve my problem.

eric_in_sd

Sounds reasonable. I was going to speculate similar but really don't know much about it. There is a slew of computer systems that mate to the key. I recall having to prove ownership to change the transmission.

If there's fouling in the injectors or head or combustion chamber, you need to run a PEA (or related) additive to dissolve the deposits. Changing the spark plugs won't do much.

machadosl

Exactly, twice a year I have this problem as my car seats on the garage for more than a month, firstly I try using these additives, but now, when I took off the spark plugs I saw they had a red color near the electrodes, so I decided to replace then. Unfortunately, I see this is is becoming frequent as we don't have gasoline, we have gasoline mixed with 27% to 28% of ethanol. I think it is impossible to program the ECU to accept this, well, I could not find how to using Star Diagnosis.

eric_in_sd

I forgot, Brazil doesn't have gasohol, it has alcogas. Maybe Bolsonaro will roll back the support of the sugar cane farmers. We do the same thing here in America; we make farmers rich, so we drive cars, burning food, to work at the food bank and distribute food to poor people.
I don't think the issue is with air/fuel ratio. The motor might make more power with proper tuning; possibly the alcohol contributes too much oxygen, so the ECU runs the motor lean ... that sounds like what your plugs are telling you. It shouldn't be a big effect, though.
Proper tuning wouldn't stop the real problem due to the atmospheric moisture being drawn into the fuel by the alcohol. I assume your air is humid; you don't live in the high plains of western Brazil, do you? If you have to store the vehicle, top it up with gas and put in a gasoline stabilizer.

You could run the fuel through a molecular sieve ... but frankly you'd be more likely to die in a fire than save your engine.

machadosl

Hahahahahahaha perfect Eric! Thank you for the explanation and I will follow your advice using gasoline stabilizer. Fortunately I live in front of the sea, but sometimes the humidity is my problem.
Thank you!

bhuter24

Yes I am still trying to figure out the problems.
Finally weather got a lot better and can work outside on the car again.
Yesterday I found a connector not plugged on the front bumper right by the washer fluid. cleaned the ambient sensor, connector, and newly fount connector and plug them. Now the temperature is displaying correct outside temp. Check engine light has not come back on yet. Vehicle seems to be running fine so far (approx. 10 minutes drive) will get back with more update, no misfire, codes or stalling yet. I am not thinking that the problem has been solved yet.
I am planning to check every electric connection now since I found one just laying there.

Will keep you guys posted.

bhuter24

Can anyone tell me where can I find the crank position sensor wire diagram?