Replace ECM. Yes or No

[Leaky88]

Hi,

 

Do not want to wrongly blame ECM much less buy one needlessly. Lot of articles and Truckers say ECM’s rarely go bad. 

So, one last sanity check to be sure.  My understanding is as follows:

-          WTS should “always” illuminate immediately after switch is turned on.  (I’m told it indicates computer has “booted” up.)

-          Once WTS goes off, I should “always” be able to bump engine and hear LIFT pump cycle for 25s.

Q1. Should the above events take place every single time?

What I know: 

Batteries are good. Charged and tested with DEAD Load tester.  Alternator is charging. Noise is .03-.04 max. (Not perfect, but don’t believe it’s a show stopper.)  

ALL grounds were lifted, cleaned to brightness, greased, and retightened.

Stock truck: Only work -outside of maintenance- is:

Installed:

1)      mechanical Fuel Pressure gauge.

2)      FASS LIFT pump – relocated from engine to tank

3)      “Protected” Isolation relay (NAPA AR272) to power LIFT

 

Truck bought used.  Not 100% sure WTS came on instantly day of purchase. (my BAD)

 I know it came on. I would wait for it to go out and then start engine.  Truck started and ran fine.  Installed FP gauge, discovered low pressure, replaced/replumbed LIFT with Isolation relay, truck started and ran fine.  Then, once after it sit for 2 weeks, I discovered the LIFT would not cycle after engine bump nor start. Pump works fine with direct power. Relay swapped, same problem.  This morning, I attempted to START truck.  Turned key on, it took 5s (1001, 1002 etc.)  for WTS to come on.  I bumped engine, LIFT pump cycled and built pressure.  Turned key off and back on.  WTS came on after count of 9s. 

Sometimes, I turn the key on and there is no WTS.  I bump engine, and there is no LIFT pump action. No Check Engine Light, and NO CODES.  Using an ACTRON CP9670.

I’ve looked at BASIC mods done, took a week, reviewed again, and find nothing wrong.

 

One last question. 

Q2. Can anyone speak to a known quality rebuilder? 

Thanks.

Leaky

[Mopar1973Man]

12 minutes ago, Leaky88 said:

ALL grounds were lifted, cleaned to brightness, greased, and retightened.

 

There is only one ground to worry about. The passenger side battery terminal. This is the master ground for all the computers. None of the computers get ground from the chassis or block.

 

12 minutes ago, Leaky88 said:

Alternator is charging. Noise is .03-.04 max. (Not perfect, but don’t believe it’s a show stopper.)  

Are there any noise filters, extra grounds, or wiring modification done? If so remove them all and retest I'll bet your AC noise test will be higher yet and most likely failing.

 

12 minutes ago, Leaky88 said:

This morning, I attempted to START truck.  Turned key on, it took 5s (1001, 1002 etc.)  for WTS to come on.  I bumped engine, LIFT pump cycled and built pressure.  Turned key off and back on.  WTS came on after count of 9s. 

Sometimes, I turn the key on and there is no WTS.  I bump engine, and there is no LIFT pump action. No Check Engine Light, and NO CODES.  Using an ACTRON CP9670.

 

If the WTS light does not come on then the ECM is not booted. There will be nothing data  or function from the ECM. No codes, no lift pump and starting. This is a clear sign the ECM is dead at that time. Kind of like attempting to read a Data CD in the CD-ROM without booting the computer first. There is no error codes and CD-ROM doesn't read anything. 

 

 

Edited June 10, 2017 by Mopar1973Man

[Leaky88]

Moparman,

Got it.  Thanks.  I need to bite the bullet and buy an ECM.

Every time I've been ready to take the plunge, I second guess myself hoping there's something missed.  

For sure the Master Ground (115? or the one your finger was pointing to in your article) is spotless.  

I am VERY interested in AC noise issue.  I have a new DIODE pack.  Seems like there should be a way to add more stages of rectification to clean it up.

Thanks.

Leaky 

[Mopar1973Man]

2 minutes ago, Leaky88 said:

For sure the Master Ground (115? or the one your finger was pointing to in your article) is spotless.  

 

That is the most important... The rest are secondary grounds like lighting and horn. Lot of sanding and scrubbing for nothing to gain nothing. 

 

3 minutes ago, Leaky88 said:

Seems like there should be a way to add more stages of rectification to clean it up.

 

Solution is easy reduce the loads on the alternator and never leave heavy loads on the alternator while idling. What happens in the diodes get hot and don't have the means to stay cool so they fail. Like so many people start there truck and leave them idle with the grid heaters cycling. This is really hard on the alternator attempting to hold a full charge at idle with 195A load for an alternator that only produces 140A at 2,000 RPM's. This is why every year I unhook my grid heaters in April and hook them back up in October when weather is cold and you require the grid heater to start again. 

[Leaky88]

 

Re: Grid Heaters

I can just lift the 4 wires off the relays, and tape to prevent moisture/dirt?

[Mopar1973Man]

Just unhook the two wires at the battery. Nothing to tape up not short out if you unhook the power. Leave the solenoid leads alone so not to trip codes.

[JAG1]

Just goes to show you have to be a member here for years before Mike begins to reveal more secrets. lol

[Leaky88]

As a new, "hungry for knowledge" guy to Diesels, I read/watch anything and everything he puts out. 

MHO, he is a renown expert whom I hope to personally meet sometime. 

[Mopar1973Man]

33 minutes ago, Leaky88 said:

As a new, "hungry for knowledge" guy to Diesels, I read/watch anything and everything he puts out. 

MHO, he is a renown expert whom I hope to personally meet sometime. 

 

Thank you... I've got lots of secrets in my head. I try to post all my finding and tricks in the articls but sometimes I'm just busy and slow to update my notes... August we are having a get togeether in Catfish junction, OR for the eclipse good time to meet us.