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Intermittent Surging and ECT

sethreesh
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LorenS

LorenS

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11 hours ago, sethreesh said:

Loren do you know exactly where that is in the loom I have the loom opened up from the ECM to where it begins to dip below the power steering pump and I don’t see it

I'm afraid I don't know, just that it's supposedly by the ECM.  Your method of starting at the ECM (or elsewhere) and removing loom is what I'd do.  Personally, whatever I opened up I'd just replace with new since it gets all brittle.

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sethreesh

sethreesh

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Well guys here with an update I got the ECM and PCM out along with both harnesses out. It's currently on route to @Auto Computer Specialist. Should be there this Thursday. Let's hope they are able to figure out this rouge electrical problem. Those harnesses get pretty nasty I pulled all the old brittle plastic insulation off cleaned off all the old tape. The splice looked in good condition but I didn't break into it. For those wondering splice S165 sat just below the power steering pump on my truck. 

 

While all that stuff is out for the next few weeks any one have suggestions on what I should do to continue making this baby shine? I have a BHAF sitting waiting to be put in when I put everything else back in for the electrical problems.

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sethreesh

sethreesh

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1 minute ago, Silverwolf2691 said:

Have you thought about the actual sensor being bad? I know you already sent it out though.. 

 

Unless i missed where you mentioned your results with the sender :think: :shrug:

I did that as my very first step of troubleshooting. Put in a ECT from NAPA still had problems. Did a bunch of other troubleshooting. Thought maybe the NAPA one was bad so I pump in one from Cummins still had problems. With it unplug and multimeter on the ECT sensor you can watch resistance change as temp increases.

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sethreesh

sethreesh

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18 minutes ago, Mopar1973Man said:

Another clue... if the ground side is lost it will peg at 240F. (High volt code) If the +5V is shorted to ground the temp will fall to -40F. (Low volt code). I'm going to assume you have a short to ground between +5V line.

 

I'm really interested in where the short is at. The tan/black wire from the ECM to ECT is a brand new pinned in wire. All the sensor grounds tested less than .2 ohms each last night from the ECM plug to the sensor. I sat on the kitchen floor with it all laid out and tested each point. This is driving me. Interesting that I am not getting any codes from this. Only way to get a code is to unplug the sensor. The P1693 was stuck in for a while but when I did the W-T mod that went away. But hey at least I'm not paying diesel prices in WA right now....have to find the bright side. 

Edited by sethreesh
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sethreesh

sethreesh

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So tan/black to battery ground? Just making sure I understand. You’re saying the short could be in that signal causing the error. And it’s probably a small break so it’s intermittent 

Edited by sethreesh
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Mopar1973Man

Mopar1973Man

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Don't confuse the sensor ground for frame ground. They are not the same.

 

Tan/Black is +5V signal. If this is shorted to ground (body) will produce you issue. So I'd you unplug both the ECT sensor and ECM then measure ohm between black/tan to block should show a short (0 ohm) but being intermittent it may not. Still in all the black/tan goes directly to the ECM.

 

Black/light blue is sensor ground back to the ECM this is shared by other sensors (APPS sensor, WIF sensor, cam sensor, etc.)

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sethreesh

sethreesh

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Hey guys while the ECM/PCM/Wiring Harness are at the @Auto Computer Specialist shop I am reviewing the grounds again just to triple check and make sure I have all the major ones. Want to check with you guys to see if I'm missing anything. So far I have cleaned up:

 

Outside The Cab

1. Driver side battery ground to engine just below the power steering pump on the timing case.

2. Driver side battery to frame mount for the front bumper

3. Driver side battery to body on the fender

4. The G100 just behind the driver side head light

5. Additional ground by G100 (two leads going to it; which one is this?)

6. Just aft of the PDC bolted to ABS controller coming out of wiring harness (not sure which one this is to)

7. Passenger side battery to PCM

8. Passenger side battery Engine

9. Passenger side battery to Body

10. Just above starter below ECM

11. W-T mod on timing case

 

Inside The Cab

1. Two sets on driver side kickplate

2. Centerline in dash frame below radio

 

Let me know what I'm missing. Thanks guys.

 

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Mopar1973Man

Mopar1973Man

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Oh my Gawd. :rolleyes:

 

The only one is the passenger battery lead. The rest of those are lights and nothing major. W-T ground wire mod deals with this directly. Again passenger battery negative covers ECM, PCM, and VP44.

 

Being all sensors rely on ECM internal ground this means the W-T ground mod resolves most of this. 

 

Again being that ECT is not pegging out and dropping this is the ECT shorting to ground. If you did the W-T ground you would have the loom exposed most of the way to the ECM. Even having @Auto Computer Specialist do the testing too will resolve this.

Edited by Mopar1973Man
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  • 2 weeks later...
LorenS

LorenS

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3 hours ago, sethreesh said:

Anything to look out for when I put them back in? 

In my case, squirrels. Tore up a big chunk of my harness! Critter Ridder applied every couple weeks didn't prevent another nest, but no more damage. Now trying moth balls tied up in an old sock...

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