1998 Chapparral 2335SS alarm issue trouble code 14

Hello everyone. New to this forum and in need of some help.
I have a problem that I cant seem to get to the bottom of. I have repowered my 1998 2335SS, Bravo 3,Mercruiser 5.7 EFI gen+. Due to my lack of inspection, bad riser and leaked into the cylinder through the exhaust valves rusting the pistons to the cylinders over the winter. New everything except alternator. Serial number OLO12155. I put her in the water two weekends ago and ran up and down the river for a good day of break in. Ran perfect like the new engine it is. I kept everything basically stock. I am running at about 70PSI oil pressure, 170 to 180 temp with a 160 thermostat depending on the load it's under. I only idled it through the no wake zones and back to 2500 through 3800 rpm during the eight hours of running we did. Put it back on the trailer and headed home to wash and flush with fresh tap water. Nothing changed until this weekend. Same thing, put her in the water ran it hard for a while. half way through the day, alarms went off causing it to go into a sort of limp mode? idles fine in neutral and under load until the RPM hits 1800 to 2000. Alarms constant until I limited it to the 1500 RPM range. looked up in my manual (service manual number 24) the diagnostic test for the trouble code 14 "Coolant Sensor Voltage High (cold). I am using the Codemate ECM trouble code tool. As I followed the diagnoses tool and had the 12 code three times and then the 14 code three times back to 12 again. I replaced the Engine Coolant Sensor even though it tested at 2600 ohm range which is normal at outside temperature 80 degrees here today. I also checked the voltage with the key on and had the required 5volts between wires 410 yellow + and wire 814 black -. there are no reasons I can find for this code. There are no water blockages pump works well and the oil pressure is great. This is a sensor that controls fuel delivery not the temperature sending unit to the gauge. I consider myself very good with engines and electronics. Auto mechanic for many years before I got my Masters License in electric. I'm not a professional marine mechanic but I understand all the concepts. I don't want to be a part changer so I am asking for advice as to further troubleshoot this issue. I guess the MAP sensor could cause this issue too but the trouble code is specific to the ECS. grounding is good the batteries are brand new and charged. This has to be a sensor causing the ECM to alter fuel delivery. Did I mention it does surge while it is alarm. I checked the Cap rotor and a couple spark plugs and all are in perfect new condition. I could see some misfire and rough idle if it were an issue with the ignition system but not a full alarm and change in fuel delivery. I have also checked the connections to the ECM (EEFI1 or 2 I'm not sure) and they are clean. I traced the wiring looking for any damage and found none. I really hope its not an ECM issue. The MAP sensor will be my next route. The issue persists after the code is cleared and I run the boat on the hose in neutral and in gear. The code 14 is thrown at each attempt. Thank you in advance for any direction that you can give.

I found code 14 listed as "overspeed" .The Bravo dosent use a shiftinterupt switch for shifting it uses it to sense if the drive is in gear or not That could be triggering the alarm

Bt Doctur said:

I found code 14 listed as "overspeed" .The Bravo dosent use a shiftinterupt switch for shifting it uses it to sense if the drive is in gear or not That could be triggering the alarm

Click to expand...

Here are the codes that apply to my engine according to my Shop manual #24.
How would overspeed work? In gear under load at 2000 RPM? What sensor would record this? It was a 14 code for sure but in case I see #24 is a speed sensor but I don't have such a sensor that I am aware of. For information, there was never a crank sensor on this engine either. Any help or advice is greatly appreciated.


GM Marine EFI Trouble Codes

Code Description


13 Oxygen Sensor Inactive
14 Coolant Sensor Voltage High (cold)
15 Coolant Sensor Voltage Low (hot)
21 Throttle Position Sensor Voltage High
22 Throttle Position Sensor Voltage Low
23 Manifold Air Temp Sensor High (cold)
24 Speed Sensor Inactive (if installed)
25 Manifold Air Temp Sensor Low (hot)
31 Governor Not Tracking
32 EGR Valve Not Tracking (if installed)
33 Manifold Absolute Pressure Sensor High
34 Manifold Absolute Pressure Sensor Low
41 Electronic Spark Timing Open Circuit
42 Electronic Spark Timing Grounded Circuit
43 Electronic Spark Control Detects Continuous Knock
44 Electronic Spark Control Cannot Detect Knock
45 Coil Driver Fault
51 ECM Calibration Checksum Error
52 ECM Hardware Failure
54 Oxygen Sensor Lean
55 Oxygen Sensor Rich
61 Fuel Pressure Sensor High
62 Fuel Pressure Sensor Low
81 (multiple causes, use scan tool to determine cause)

Here is what I have that applies to my service manual #24. How would overspeed work? Please help me understand. What sensor would sense the overspeed and at what RPM? I don't have a speed sensor or a crank sensor on this engine. Why would it go into alarm while in gear, on plane at 3800 RPM and put me in a limited "limp mode?" until I back down to 1500 rpm? I can go out right now and start it up on the hose and let it warm up until the thermostat opens, increase throttle in gear or in neutral to 1800/ 2000 rpm and get the constant alarm. the engine surges while in alarm from erratic fuel delivery. once I bring the throttle back to 1500 the alarm goes away and runs properly. The code is again present upon shut down and the code reader is turned on in service mode. I am open to any advice and directions, Thanks.
GM Marine EFI Trouble Codes

Code Description


13 Oxygen Sensor Inactive
14 Coolant Sensor Voltage High (cold)
15 Coolant Sensor Voltage Low (hot)
21 Throttle Position Sensor Voltage High
22 Throttle Position Sensor Voltage Low
23 Manifold Air Temp Sensor High (cold)
24 Speed Sensor Inactive (if installed)
25 Manifold Air Temp Sensor Low (hot)
31 Governor Not Tracking
32 EGR Valve Not Tracking (if installed)
33 Manifold Absolute Pressure Sensor High
34 Manifold Absolute Pressure Sensor Low
41 Electronic Spark Timing Open Circuit
42 Electronic Spark Timing Grounded Circuit
43 Electronic Spark Control Detects Continuous Knock
44 Electronic Spark Control Cannot Detect Knock
45 Coil Driver Fault
51 ECM Calibration Checksum Error
52 ECM Hardware Failure
54 Oxygen Sensor Lean
55 Oxygen Sensor Rich
61 Fuel Pressure Sensor High
62 Fuel Pressure Sensor Low
81 (multiple causes, use scan tool to determine cause)

Manual #24 appears correct for the application and shows 14 as the ECT...have you followed the troubleshooting chart in section 5G, for the DTC14?

Sometimes, you have to take the scantool out on the boat and run it to find the issue....

Based on your auto background, the ECU in your boat is comparable to a mid-80's GM ECU....and you'll find many of the codes are the same....

Yes sir, I have been through the complete troubleshooting. I stated my findings in my original post. I do have the required voltage at wires 410 and 814. 5.3 volts to be exact. I just put a new wire connector for the sensor P/N #805218T on will call. I have no way of telling if the connector has a low enough resistance or if it getting a false resistance through the connector or wire. I really didn't want to sink the money into a full scantool. If the new connector proves not to be the issue I may have to go that route. Thanks for the reply.

Ha ha ha take a hammer and smash the alarm! Problem solved!

makomark said:

Manual #24 appears correct for the application and shows 14 as the ECT...have you followed the troubleshooting chart in section 5G, for the DTC14?

Sometimes, you have to take the scantool out on the boat and run it to find the issue....

Based on your auto background, the ECU in your boat is comparable to a mid-80's GM ECU....and you'll find many of the codes are the same....

Click to expand...

I'm sorry I have not followed the 5G section. I will be doing that this evening. I totally missed it. Thanks.

Bt Doctur said:

I found code 14 listed as "overspeed" .The Bravo dosent use a shiftinterupt switch for shifting it uses it to sense if the drive is in gear or not That could be triggering the alarm

Click to expand...

Bt DOctur, please explain, you may have the answer I am looking for. Where is code 14 an overspeed? I can't find error codes with that error but this is how I learn. I found a thread that refers to alternator outputs too high of a frequency the ECM goes into alarm and guardian mode. Am I on the right track? I have done all the testing listed for the trouble code 14 "ETS temp too low " and everything is perfect to the ECM. I am hopeful that it ,is that simple. I remembered hearing an intermittent noise that sounded like it may have been an accessory with a failing bearing. Never thought much of it because the voltage gauge was at 13 to 14DC volts. I look forward to your input. Thanks

On a Bravo drive the switch interupter is not used , the switch that is there is a overspeed/over rev switch. When activated it tells the computer your in neutral and restricts the rpm

Update on the boat repairs. I gave up on the Engine Temperature Sensor and its error 14. Back to basics. put it service mode and checked & tweaked the timing. Changed the alternator due to an intermittent bearing sound, Got it running well and held the RPM at 2500 without alarm once it was at operating temperature. To my surprise I found half of the starboard exhaust flapper between the exhaust tube and the outdrive. I replaced these brand new before the new engine went in along with the bellows. (Already ordered a new set)The starboard riser was hotter to the touch compared to the port, not to the point of overheat. I am only wondering if this was the ghost I have been chasing this whole time? any input? If the flapper stuck in the Y pipe while I was running at 3800 to 4000 RPM I am guessing this could have caused my problem out of the blue.
I searched the old threads for symptoms of a failed exhaust flapper and found limited RPM and

voltxpert... did you ever resolve your issue? I'm having similar problems.

seaway11 said:

voltxpert... did you ever resolve your issue? I'm having similar problems.

Click to expand...

Well to my amazement the code 14 was a false code. I pulled the spark plugs and they were black and fouled even though they were brand new. So I changed the spark plugs, wires, cap, rotor and set the timing (while in service mode). Ran great with no fault alarms. I thought I had set the timing while in service mode but I second guessed myself and sure enough it was off. May have slipped when torqueing the distributor tie down. Either way go back to basics. Good luck