ECM change

Tiny
JASON MARTIN
  • MEMBER
  • 2002 DODGE TRUCK
  • 4.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 174,000 MILES
I accidentally fried the brain on my truck.
Ordered a "plug and play" with the correct matching number. But it still will not start.
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Saturday, March 11th, 2017 AT 3:51 PM

14 Replies

Tiny
MHPAUTOS
  • EXPERT
Any codes? It may not be talking to the key reader. I would be looking here.
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Saturday, March 11th, 2017 AT 3:57 PM
Tiny
JASON MARTIN
  • MEMBER
Okay, it says po135 and po141.
Also, why is my ABS light blinking and dinging and I have to press on the gas or else my truck will not stay running?
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Sunday, March 12th, 2017 AT 4:20 PM
Tiny
CARADIODOC
  • EXPERT
How did you damage the Engine Computer? That is not something you can do very easily.

P0135 - Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0140 - Oxygen Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

Those codes are not related to a crank/no-start condition unless the wiring harness fell down onto hot exhaust parts and grounded out.

Do not pay any attention to the low idle speed. Since power was lost to the Engine Computer, it has to relearn "minimum throttle" before it will know when it has to be in control of idle speed. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
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Sunday, March 12th, 2017 AT 4:29 PM
Tiny
JASON MARTIN
  • MEMBER
The codes are because of the exhaust I think. I just need to know how to make that ABS stop flashing and dinging. Accidentally hooked up two wire backwards from the number one cylinder to the eight because number eight was not hitting when I bought it. So I jumped it with the number one. I had to replace the head gaskets. And that is what happened when I put it back together. So then I finally got the new brain. And now the ABS is on and flashing also my brake lights stay on.

It starts it just will not stop dinging

Also, it does not stay running, but it will fire up.
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Sunday, March 12th, 2017 AT 5:13 PM
Tiny
CARADIODOC
  • EXPERT
Did you see my explanation of minimum throttle?

Switching spark plug wires is not going to damage the Engine Computer. If it could, all kinds of people would be having problems.

If the red "Brake" warning light is on, the ABS light will turn on too. The Computer doesn't know why the red light is on. It only knows there might be a problem that prevents it from operating properly, so it turns itself off, and turns the yellow light on to tell you.

There's two things to look at to determine why the red light is on. Be sure the parking brake pedal is fully released. Check the brake fluid level in the reservoir, or unplug the level switch as a test.

If only the yellow warning light is on, you'll need a scanner to read and record the diagnostic fault codes. Those will indicate the circuit that needs further diagnosis. Once the problem is solved, on some models the only way to erase the codes and turn the light off is with a scanner. On others, the light will turn off once the problem is solved, but the codes may stay in memory.
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Monday, March 13th, 2017 AT 6:44 PM
Tiny
JASON MARTIN
  • MEMBER
It has coils not spark plug wires
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Monday, March 13th, 2017 AT 6:49 PM
Tiny
CARADIODOC
  • EXPERT
Same difference. The computer doesn't care which ignition coil is hooked to which plug. The timing will be wrong, but that won't hurt the computer.
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Monday, March 13th, 2017 AT 7:05 PM
Tiny
JASON MARTIN
  • MEMBER
Whatever dude you must not be hearing me. My question had nothing to do with weather or not I'm capable of frying a brain. I'm wanting to know why it won't turn off (the red abs light that dings and flshrs. And yes I made sure the e brake isn't on. And I have a scanner. And I have already told you what coded it has read
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Monday, March 13th, 2017 AT 8:04 PM
Tiny
JASON MARTIN
  • MEMBER
Also the brake warning light isn't on just the abs
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Monday, March 13th, 2017 AT 8:06 PM
Tiny
CARADIODOC
  • EXPERT
You really have me confused. There is no such thing on any car as a red ABS light. When the ABS system shuts down due to a detected defect, the computer turns on the yellow "ABS" light. That light never flashes, except on older models while you're flashing out fault codes in test mode.

You listed two fault codes in the Engine Computer. That is a red warning light. If that light flashes, that is indicating the most serious of conditions. Too much unburned fuel is going into the exhaust system where it will burn in the catalytic converter and damage it. You're supposed to stop the engine right away to avoid that damage.

You haven't listed any ABS fault codes, so I don't know why you're upset that I don't know why you're even in that system. The ABS system won't cause the dinging you referred to, and it won't cause a flashing warning light, and it won't turn on a red warning light. You need to get your description of the symptoms straight if you expect me to give you accurate diagnostic steps.

The first code you listed refers to the heater circuit in the driver's side front oxygen sensor. That circuit is simply responsible for getting the sensing element up to 600 degrees sooner than the hot exhaust can do on its own. That reduces emissions. Any defect that could potentially adversely affect emissions will turn on the red Check Engine light.

The second code refers to the passenger side rear oxygen sensor. Electrically it is okay since no fault code was set related to an electrical failure. The sensor is not developing an output voltage signal. You have to determine if that is due to contamination on the sensing element, or if no change in the exhaust gas is taking place in the catalytic converter. Usually that code is caused by a failed sensor.

Neither of those codes refer to a defect that will have any noticeable effect on engine performance. If the red Check Engine light didn't turn on, you'd never know those codes were set. Also, neither of those codes refer to anything that will cause excessive fuel to be dumped into the exhaust system. There has to be some other fault code in the Engine Computer related to that. Most commonly the code will refer to a specific cylinder misfire, and that is usually a spark-related problem.

Rather than relying on the scanner, read the fault codes directly to see if any others show up.
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Tuesday, March 14th, 2017 AT 5:53 PM
Tiny
JASON MARTIN
  • MEMBER
Ok my apology it's a yellow abs light
And it flashes and dings.
The reason for the first codes is due to the catalytic converter not being on the truck.
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Wednesday, March 15th, 2017 AT 6:32 AM
Tiny
CARADIODOC
  • EXPERT
Now I'm going to add even more confusion to this story. I'm a Dodge specialist and a brake system specialist, but I never ran into a flashing yellow warning light. Turns out this system can turn on the red AND yellow warning lights, and it can flash the yellow one. Both will be on when there is a diagnostic fault code in the ABS Computer.

There's two things to consider when the yellow light is flashing. First, read and record the diagnostic fault codes. Those will indicate the circuit that needs further diagnosis, or the unacceptable operating condition. Hopefully there will be a code related to a missing wheel speed signal.

The yellow warning light will flash if "a vehicle speed signal parameter is faulty or missing". There should be a fault code related to that. Also, the yellow light will flash if "the axle type or tire size are not programmed properly".

There's two different ABS systems available for this truck. One is a four-wheel system, and one is rear-wheel-ABS. The easiest way to tell which you have is the four-wheel system will have a wheel speed sensor at each front wheel. The two rear wheels are modulated together on the four-wheel system.

If you get a fault code for a missing rear wheel speed signal, (this is different from an electrical circuit problem with that sensor), look for a sensor on top of the differential housing. Pull it out and check for "hair" growing on the end where the magnet sticks out. Any metallic debris that collects there will reduce the sensor's ability to generate a signal.

For future reference, the pump motor is tested when the truck reaches 15 mph. If the yellow light doesn't turn on until you reach that speed, it's the pump circuit that needs to be diagnosed.

In the '90s, most aftermarket scanners were not capable of accessing ABS Computers and reading their fault codes. I have a Chrysler DRB3 for all of my vehicles. If you need to find one, a lot of independent shops bought them because with an additional plug-in card, it will do emissions-related stuff on any brand of car sold in the U.S. Starting with '96 models. I suspect the newer aftermarket scanners today will access the ABS Computers on a 2002 model by now.
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Wednesday, March 15th, 2017 AT 5:30 PM
Tiny
JASON MARTIN
  • MEMBER
Ok can you tell me how exactly to go about taking that sensor off the back you know the one with the "hairs"
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Monday, April 3rd, 2017 AT 12:40 AM
Tiny
CARADIODOC
  • EXPERT
The ones I'm familiar with had a 10 mm nut to remove, then the sensor and a metal shield right over it were lifted out of the housing. If it's contaminated with metal particles, it will look like a black or brown goo on the end, with the consistency similar to pasta sauce. Wipe that off with a rag, then reinstall the sensor.
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Monday, April 3rd, 2017 AT 3:48 PM

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