EST1 Open

[300sflyer]

Working on a 2007 MPI 4.3L, [SN 1A041962] and have a few issues. First is the EST1 Open code that keeps coming back within the Diacom software. The engine appears to be running just fine on all 6 cylinders, I have checked the ignition wires, and the plugs look good. I can delete the code while the engine is running, and it is gone. Turn the key off and then back on, and the code reappears? Maybe this is normal?

Along with this, I have 2 beeps every minute from the alarm system, and two beeps when I first turn the key on. Not sure if it is related to the first issue?

Lastly is the temperature gauge. I have replaced both the sending unit, and the gauge with new ones, and yet it still says the engine is running at 190F, when in reality it is at 160F, verified by the scan, and by a laser temp gauge. Perhaps this is related to the 2 beeps each minute?

Thanks for your help folks!

 

[alldodge]

Your S/N (thanks) shows a 555 ECM
The EST 1 (Electronic Spark Timing) means there is an issue with plug number 1 and its open. If it was ECT (Engine Coolant Temp) which is what you have been looking at.

If it is EST then check your plug, plug wires, Dist Cap and Rotor

 

[300sflyer]

Thanks for the info. I did swap the sparkplugs and ignition wires on cylinders one & two, but it made no difference. Guess I will check the cap and rotor next.

Any thoughts on the alarm and the temperature gauge?

 

[alldodge]

The Temp gauge and ECM readings do not connect with each other. The gauge could show over 300 and the ECM doesn't care.

2 Beeps can mean any of the items

 

[300sflyer]

Thanks for the chart! It had 100% power available during the scan, so I am going to assume the alarm beeps are related to EST1 open code as well. That chart narrowed down the possibilities.

Where does the ECM get its coolant temperature reading from? Does it use the gauge sending unit, or something else?

Thanks!

 

[alldodge]

Both sensors are on the thermostat housing, gauge on one side and ECM on the other

 

[300sflyer]

I have installed new plugs, wires, cap and rotor and still have the two warning beeps every minute, and the EST1 open code showing up. Again, the engine seems to run just fine.

I am puzzled, and don't know what else to try?

Thanks.

 

[muc]

I am puzzled, and don't know what else to try.

Might want to try the trouble shooting tree in the service manual. If I remember correctly it will have you test for voltage and continuity in a few places.

I’m going off of memory here. There are 3 revisions of the ECM 555 manual. At least one of them will have the reason as to why this code only sets when you first turn the key on. Some codes only set when there is no RPM reference and some only set when there is a RPM reference. EST open codes only set KOEO.
Some ECM 555 engines will only set EST 1 codes (no 2-8 codes) because there is only one coil and the ECM doesn’t know what cylinder is firing at any given time. The only way the ECM could know is if your engine uses the cam sensor in the distributor. Some do, some don’t.

The sending unit for the temp gauge will have only one wire. The temp sender for the ECM will have 2 wires.

 

[300sflyer]

I have service manual #36. Not sure if it is the correct one for this engine, from the 3 different ones?

Thanks.

 

[300sflyer]

Still trying to figure this out. If there was a open circuit somewhere in the ignition coil itself, would the engine even run?

Thanks.

 

[alldodge]

No clue right now, all connections are good, might be the ECM has an internal problem. Could get it tested,
https://www.boatunlimited.com/marine-ecm-testing-and-repair/

 

[dubs283]

Still trying to figure this out. If there was a open circuit somewhere in the ignition coil itself, would the engine even run?

Maybe, but could be there is a connection issue somewhere. Either a harness plug/receptacle, ground, or wire issue in the harness.

Or, the ecm has failed internally. Not likely but possible

At this point your best interest is to inspect connections (especially those related to ignition), harness, grounds, battery connections, etc. Look for corrosion, broken wires, do a wiggle test

 

[muc]

I have service manual #36. Not sure if it is the correct one for this engine, from the 3 different ones?

Thanks.

What is the part number and date on your manual?

 

[300sflyer]

What is the part number and date on your manual?

Part # 90-864573 February 2002

 

[muc]

Part # 90-864573 February 2002

That wasn't a very good manual.
90-8M0160555 JANUARY 2020
Is much better. $31.00 and worth it.

Your manual page 3A-14 has the wiring diagram for the coil harness.
check for battery voltage and a good ground where they should be and check all the wires for continuity. If everything is good replace the coil/driver module. Use the steps on pages 2A-17+18

Because this is a KOEO code the plugs, plug wires and dist cap (secondary ignition) can't cause it.

Because this is an EST open only use 3.2 3.3 3.4 on page 2A-43

The ECM isn't seeing the correct signal at pin 23 at key on.

VERY VERY small chance it's the ECM.

 

[300sflyer]

Found the problem causing the code and the alarm beeps. The ignition coil / rectifier was the issue. New one installed, and good to go.

Now if I can just figure out why the temp gauge isn't reading properly. New gauge, new sender, actual engine temperature at 158F, [varified with scan and laser temp gauge] and yet the gauge reads at about 200F. Very strange...

 

[alldodge]

Good deal

What's the part number of the sender?

 

[300sflyer]

Faria 33851 gauge cluster, with Sierra 18-5897 sender.

 

[alldodge]

Sender checks out for 240 (cold) to 33 (hot) ohms
Put sender in pan a water with thermometer and ohm meter connected to see how it changes as water heats up

 

[300sflyer]

Finally got around to checking the senders. Both the original sender and the new one are spot on. Given that this is a brand new gauge, [old one did the same thing] there must be something else happening... but what?