Replaced battery and now in engine failsafe mode

[jcrisp05]

2005 mercury mountaineer 4.0 v6 awd.

Replaced bad battery with a new agm battery.
When i attempted to start after it didnt want to and when it did it went into the engine failsafe mode.

I have cleaned the throttlebody whilst having the battery disconnected to try and clear codes.

When its running in the engine failsafe mode it will go into gear but i have no pedal.

I dont have a scanner, and only way its making it to a parts store to scan it is by tow. So I need help. Did the new battery ruin the throttle body?

 

[imp]

2005 mercury mountaineer 4.0 v6 awd.

Replaced bad battery with a new agm battery.
When i attempted to start after it didnt want to and when it did it went into the engine failsafe mode.

I have cleaned the throttlebody whilst having the battery disconnected to try and clear codes.

When its running in the engine failsafe mode it will go into gear but i have no pedal.

I dont have a scanner, and only way its making it to a parts store to scan it is by tow. So I need help. Did the new battery ruin the throttle body?

What led you to the throttle body, anyway? You have drive by wire, in which TB malfunction CAN and often DOES cause fail-safe (limp) mode. Any chance wiring got screwed up? You really need to buy a good code-reader.......

 

[jcrisp05]

What led you to the throttle body, anyway? You have drive by wire, in which TB malfunction CAN and often DOES cause fail-safe (limp) mode. Any chance wiring got screwed up? You really need to buy a good code-reader.......

Everything was fine when i pulled it into the garage, shut it off replaced battery and on startup this happened.

Forums plus the pedal not doing anything led me to throttlebody. Loads of forums talking about cleaning throttlebody(which it was pretty nasty).
I do really need a good code scanner but also dont have the money for everything at this exact time.

I guess there is always a chance with the wiring. I was hoping to find a way to confirm the throttlebody without just blindly spending 100 bucks on a new one.

 

[jcrisp05]

What led you to the throttle body, anyway? You have drive by wire, in which TB malfunction CAN and often DOES cause fail-safe (limp) mode. Any chance wiring got screwed up? You really need to buy a good code-reader.......

Everything was fine when i pulled it into the garage, shut it off replaced battery and on startup this happened.

Forums plus the pedal not doing anything led me to throttlebody. Loads of forums talking about cleaning throttlebody(which it was pretty nasty).
I do really need a good code scanner but also dont have the money for everything at this exact time.

I guess there is always a chance with the wiring. I was hoping to find a way to confirm the throttlebody without just blindly spending 100 bucks on a new one.

 

[1991 sploder]

That's going to be an issue most likely there's multiple codes shutting it down like tps cam position crank position sensors.
Try disconnect the battery for a while making sure it has at least 12.3v when you start it... Could be low running voltage 14.8 is optimal.

 

[jcrisp05]

Left the battery disconnected overnight, hooked it up, turned the key to the on position before starting and it still said engine failsafe mode. Started it and still in failsafe, still when i hit the pedal nothing happens.

No luck on anyone i know having a scanner i could use. I think i will go buy a throttle actuator motor and replace it and see if thats it.

 

[jcrisp05]

Rented a scanner tool from autozone, throws a throttle actuator stuck closed and a throttle forced idle or something like that. Im going to tak the throttle body back apart and try a deeper cleaning before replacing

 

[imp]

Left the battery disconnected overnight, hooked it up, turned the key to the on position before starting and it still said engine failsafe mode. Started it and still in failsafe, still when i hit the pedal nothing happens.

No luck on anyone i know having a scanner i could use. I think i will go buy a throttle actuator motor and replace it and see if thats it.

The throttle actuator motor is self-checking. It does a maneuver every single time the key is turned to "ON", and this fact can be checked yourself to confirm it's doing it.

"Rest" position for the throttle plate with key OFF is very slightly open; you can see the gap with inlet duct removed. Upon key turned to "ON", the plate quickly closes shut tight, then returns to "rest" position, slightly open. Key to "START" opens throttle plate wide open while cranking.

Purpose of this "self-check" is to verify, every single start-up cycle, that the Throttle Position Sensor is working properly; it's output is checked very quickly as the plate closes down, then back to rest position. Reason this was incorporated, good for Ford, was a bunch of Japanese-built cars with early drive by wire in the 2000s went wide open throttle by themselves, causing numerous accidents and injury claims. Early systems used only a rheostat type variable resistor to input voltage to the throttle plate motor. Ford uses a double-rheostat with two variable connections: when gas pedal is depressed, the voltages on each wiper move in opposite polarities. If they are not identical in value, but opposite polarity, limp mode is immediately entered.

I checked my own 2004 as described above. The plate-close-open maneuver happens quickly, about 1 second of time overall, not noticeable when turning key beyond ON to START. Try it!

 

[imp]

Rented a scanner tool from autozone, throws a throttle actuator stuck closed and a throttle forced idle or something like that. Im going to tak the throttle body back apart and try a deeper cleaning before replacing

Rented a scanner tool from autozone, throws a throttle actuator stuck closed and a throttle forced idle or something like that. Im going to tak the throttle body back apart and try a deeper cleaning before replacing

That is exactly what mine did: "stuck closed" and "forced idle". I took the body apart, figured out how it worked, gave up on fixing it. Uses a big clock-spring to return throttle plate when off gas pedal, a very short movement spring-loaded tiny plunger to push plate slightly open when at rest. I replaced the entire T.B. assembly, works fine. Before going that far, you might want to try replacement of the Throttle Position Sensor, it's replaceable. Though, I expect if it were the culprit, a code would say so, but maybe not. Ford does not wan t us messing with (or understanding) high-cost litigation producing items. Good luck. imp

 

[jcrisp05]

The throttle actuator motor is self-checking. It does a maneuver every single time the key is turned to "ON", and this fact can be checked yourself to confirm it's doing it.

"Rest" position for the throttle plate with key OFF is very slightly open; you can see the gap with inlet duct removed. Upon key turned to "ON", the plate quickly closes shut tight, then returns to "rest" position, slightly open. Key to "START" opens throttle plate wide open while cranking.

Purpose of this "self-check" is to verify, every single start-up cycle, that the Throttle Position Sensor is working properly; it's output is checked very quickly as the plate closes down, then back to rest position. Reason this was incorporated, good for Ford, was a bunch of Japanese-built cars with early drive by wire in the 2000s went wide open throttle by themselves, causing numerous accidents and injury claims. Early systems used only a rheostat type variable resistor to input voltage to the throttle plate motor. Ford uses a double-rheostat with two variable connections: when gas pedal is depressed, the voltages on each wiper move in opposite polarities. If they are not identical in value, but opposite polarity, limp mode is immediately entered.

I checked my own 2004 as described above. The plate-close-open maneuver happens quickly, about 1 second of time overall, not noticeable when turning key beyond ON to START. Try it!

So i will try this, i took the motor actuator off the throttle body and everything looks good but the outer casing of the motor itself is somewhat corroded. The whole unit at autotheft is 250, the motor and cover is 65. Thanks for the in depth explanation.

 

[imp]

So i will try this, i took the motor actuator off the throttle body and everything looks good but the outer casing of the motor itself is somewhat corroded. The whole unit at autotheft is 250, the motor and cover is 65. Thanks for the in depth explanation.

Is it understandable? I believe very few working on vehicles are aware of the drive by wire foibles. I had to figger it out myself.

 

[jcrisp05]

Is it understandable? I believe very few working on vehicles are aware of the drive by wire foibles. I had to figger it out myself.

Yeah but ive had some experience with drive by wire vehicles. Last night i looked into how the particular pedal on these worked(i assumed a potentiometer) similar but different in reality.

 

[jcrisp05]

After disassembling and turning the motor by hand and reassembling the actuator motor. The engine failsafe mode is gone, and so is the service light. It runs and has a working accelerator pedal. Will drive it in a few to confirm fully working.

 

[jcrisp05]

Everything works as should if it acts up again i will just replace the motor, either way thanks for all the help!