EMM Problem or Main Relay? 2001 175 Fitch (no hard rails)

tcarrion

Recruit
Joined
Jan 11, 2011
Messages
4
Hi, I am from Venezuela, please forgive any grammar error.
I am having an estrange problem with my ficht. At one point I thought it was related to overheat, but now I doubt it.
The engine start perfectly, idle normal, runs great. But after I stop the engine it won't start again, at least for a while.

This is the symptom: Turn the key, the gas pump runs and the warning lights check and horn pass normal, but after a secong all warning lights are up again at the same time and the engine wont crank, no power to the starter. Turn the key off, and wait about 20 minutes, the engine start normally. Overheat? No!. I connect my laptop with the diagnostic software and the engine running at WOT never pass the 60 Celsius degrees, and the EMM never pass the 50 Celsius degrees. I checked the water cooling hoses that goes through the water separator and the EMM and they are not clogged, water pass freely. Also no error codes are registered.

Now when I try to connect the diagnostic software when the 3 lights are up (right after I turn the key back on after I ran the engine) it won't connect. It's like the EMM is dead. If I wait 20 minutes and turn the key, no lights and can connect with the DS, no error codes registered.
I checked every cable and connector, everything seems ok, but the main relay is always warm.
I am gessing that the main relay is defective and when it gets hot the EMM won't receive the whole 12 volts and turn off itself, then when the relay cool off the EMM receive again normal current and remain on allowing crank the engine. So, it could be a temperature problem, however not related to engine or EMM sensors but to a defective main relay. (Hoping is not a defective EMM)

I am about to buy a new relay and test. But before my "test" I want to know if someone here had found the solution to this issue and can direct me to the answer without my "try and error" run with the relay.
thanks and regards,
Tyrone
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: EMM Problem or Main Relay? 2001 175 Fitch (no hard rails)

Hate to say this but it sounds like a bad EMM.
 

tcarrion

Recruit
Joined
Jan 11, 2011
Messages
4
Re: EMM Problem or Main Relay? 2001 175 Fitch (no hard rails)

I know it happened to someone in this forum six years ago, it will be interesting to know if he did change the EMM or found another solution...
 

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: EMM Problem or Main Relay? 2001 175 Fitch (no hard rails)

Check the voltage going into the EMM when cranking hot engine. Those EMM's are sensitive for low voltage which may shut down the EMM. Burned 'contacts' in the relay may be one problem, another is that the engine heats UP after shut-down. This will result in increased resistance in cables etc. It may be enough amps from your battery when cranking 'cold', it may not be when cranking hot. Disconnect all ground connections on battery and engine and clean.
 

tcarrion

Recruit
Joined
Jan 11, 2011
Messages
4
Re: EMM Problem or Main Relay? 2001 175 Fitch (no hard rails)

Thanks Haffiman, will do!
However I just talked to DFITech guys and when I told them about the 3 lights up simultaniuosly they didn't hesitate to say "say no more, your computer is bad"...

I already tested the main relay and it is fine!, 68 ohms in the control switch contacts and continuity in the EMM 12 volts contacts when aply current to control switch contacts. So, main relay is not the problem.

I will check the voltage to the EMM when the 3 lights goes up and when craking hot engine... However everything points out to repair the EMM.... sadly...
 
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