Notorious No Crank No Start Solution

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Wes Henderson

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I have searched the Web to no avail. This issue affects both Ford Expeditions and Lincoln Navigators. I found many threads on the issue, but never a resolution for those of us that had a problem beyond a simple relay or the likes. After spending probably a hundred or so hours going through electrical diagrams in my FSM; testing circuits, cards, wires, connectors; and becoming frustrated beyond belief, I finally found the issue.

If you don't care much for reading, skip to the SOLUTION heading.

***SYMPTOMS & CAUSES***

Symptoms (can be all or some of the following):
-Starter relay clicks, but engine does not crank
-Service advancetrac
-Charging system data error
-Coolant temp data error
-ABS light on

Now, given the variety of issues and routing all of the circuits I found only a few points that one point of failure could affect all of those circuits.

-Fusible links
-PCM/ECM/BCM
-Interior fuse box
-PATS (Passive Anti Theft System)

***EXPLANATIONS***

The interior fuse box actually has layered pass through circuit cards built into it. With the notoriety these things have for water infiltrating through the lower passenger edge of the a-pillar, I figured it was my best bet. It can still cause a plethora ofor issues, but it was not the cause behind mine.

The fusible links can be pulled on gently to see if any sections feel "spongy". Next they can be checked at each end for resistance and continuity. Now, these are likely to have additional issues accompanying them should they fail.

The PCM/ECM/BCM is very complex, but the premise behind how it works is mostly switching grounds. It grounds the fuel injectors & spark plug coils based on cam sensor input, sends the variable duty cycle signal to the fuel pump, sends the signal to the starter and much more. The reason I mention all of those is that the three part module is passively disabled by the PATS. Essentially, it is really just "not enabled" without seeing a proper key. I could write a whole different thread on the PATS, but simply put, if your security light on the top center of the dash blinks in the regular intervals then your PATS should be fine. If it is blinking twice per second, then the PATS is disabling the vehicle. PATS failure, PCM/ECM/BCM loss of key programming, ignition key rf transceiver failure or open/shorted signal wires shouldn't be accompanied by the engine systems' data errors. The only time it will is if the loss of key programming caused the PATS inhibit and happened because of a failing PCM/ECM/BCM.

For anyone wondering about bypassing PATS... Don't bother. It took me a couple days with an oscilloscope and varying signal inputs to get the engine to run smoothly enough bypassing the ECM controls.


***SOLUTION***


Now, assuming you have checked all the basics; battery, fusible links, corrosion on battery terminals, PCM relay, starter, PATS, main fuse, etc... then the issue lies within the PCM/ECM/BCM, sort of. The module has multiple grounds. The one causing the issue is G102.

First, disconnect the battery. Open the hood and remove the three bolts holding the passenger headlight in. Disconnect and remove the headlight. Looking at where the light was, on the right, where the radiator support is, there will be a ground. This is G102. Remove the bolt, run a tap through the body, and clean the threads on the bolt. I would also recommend cutting the connection off the end and solder & heatshrink a new connection on. By the time your symptoms are this progressed, removing all the oxidation tends to thin the connector and strip the plating. Reconnect everything and start her up!

Any questions or further elaboration, feel free to respond. I only created an account here to help people with this fault specifically.
 
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CertusExpo

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I'm wondering this. Could I just add a potentiometer like this one LINK to a bypass of the fuel pump relay circuit that would allow manual voltage control for low need scenarios such as surface street driving or stop and go traffic?
Perhaps even allow one to find better "sweetspots" for both low draw (city streets or stop/go traffic) and open freeway/highway driving.

OR

Wire in one of these with pigtails in place of the OEM fuel pump relay so it's better than stock and serviceable?
 
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Bedrck47

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Do you really expect him to answer He was last on a month ago Aug 24, 2017

New member 1 post and hasn't been back since
 
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CertusExpo

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It doesn't hurt to throw it out there. I'm gonna pull a part from another Expy for the short-term as I won't know it's history or dependability.

I'm going to continue to research for an improved long-term solution. Who knows, I might be able to engineer that flaw out.

Not to mention, it's been a while since I've posted. Life has been busy.
 
OP
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Wes Henderson

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I'm wondering this. Could I just add a potentiometer like this one LINK to a bypass of the fuel pump relay circuit that would allow manual voltage control for low need scenarios such as surface street driving or stop and go traffic?
Perhaps even allow one to find better "sweetspots" for both low draw (city streets or stop/go traffic) and open freeway/highway driving.

OR

Wire in one of these with pigtails in place of the OEM fuel pump relay so it's better than stock and serviceable?

According to the fsm, the fuel pump is a variable duty cycle pump. Even after monitoring it with an oscilloscope, it would be difficult to replicate any functional purpose. I'm not exactly sure why you would need or want to mess with the fuel. Perhaps you can further enlighten me on the purpose.
 

Bedrck47

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According to the fsm, the fuel pump is a variable duty cycle pump. Even after monitoring it with an oscilloscope, it would be difficult to replicate any functional purpose. I'm not exactly sure why you would need or want to mess with the fuel. Perhaps you can further enlighten me on the purpose.

You may be correct in your description and testing of the fuel pump and I am going to assume you did this on your own expy which is an 05 model year

However the information does not apply to the OP's 04 expy Thee reason being the 04 and 05 models use different fuel pump circuits and also the 04 and 05 models use different fuel pumps modules

A simple check of the wiring diagrams in the FSM's will show the difference and a simple check of parts shown in RockAuto will show different part numbers for the fuel pump modules
 

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