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Old 08-27-2019, 11:20 PM   #1
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Default 2003 2700scr starting issues

Hi I'm new to the forum but have been reading to help figure out my issues. I have had 4 times when my boat 5.7 thunderbolt will not start, no alarm, nothing but I have lights, blower, etc. I thought it was a battery issue and replaced them, but that did not fix the issue. I'm not sure if it is the ignition switch, neutral switch or kill switch. Right now it is working, alarm and will crank, then I can go out and turn the key and nothing, no alarm no crank, completely dead. It is really hard to trouble shoot when intermittent issue. To get to the neutral switch is a major issue small space to work in, on one of the threads they talked about the slave solenoid, but that does not make sense to me. Thanks for any recommendations
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Old 08-28-2019, 12:18 AM   #2
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It's not the neutral switch or slave solenoid as that would not impact the alarm etc.... Check all the big fuses on the motor. One could be lose. It has to be a lose electrical connection.
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Old 08-28-2019, 12:37 AM   #3
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Can you rig up a voltmeter to the B terminal of the ignition switch to see if power here goes away when the issue occurs. This way you can isolate as either power not getting to the switch or not then move to the next point to monitor. You can also check the 10 pin round connector on the engine harness.
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Old 08-28-2019, 01:26 AM   #4
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I was thinking those items because the wiring schematic shows the alarm in the same wiring as the start circuit neutral switch and the emergency shut down switch. I will try to a look for loose connections and read the voltage if I can get the issue to happen again. thank you
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Old 08-28-2019, 03:09 AM   #5
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The alarm gets power from the I (ignition) terminal of the ignition switch it then goes to the kill switch and finally the engine ignition coil and Thunderbolt ignition module. The S terminal on the ignition switch is power for starting and goes to the neutral safety switch and then the slave soleniod which in tern powers the starter soleniod. This circuit has nothing to do with the alarm.
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Old 08-28-2019, 04:53 AM   #6
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Well I went out and turned the key a no alarm, dead put a volt meter on the b connection and got 2.5 volts, went to the motor and lifted the wire to the 10 pin connector and the alarm started sounding went and check the volt meter and 12.5 volts, so now I need to see if it is in the connector or the cable some where, hopefully just bad connection. thank you for all you help, I will post when I can look at some more tomorrow or this weekend.

Thanks again
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Old 08-28-2019, 12:47 PM   #7
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Disconnect the connector and inspect the large pin for corrosion.
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Old 09-04-2019, 08:11 PM   #8
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Well last night I put everything back together, I did not see any corrosion on the connector, the alarm is on now so 12v to the ignition switch , tried to see if I could get the alarm to fail by moving wires around motor, but no luck. Still don't feel confident, I will try to check fuses, but electrical is working so loose connections are hard to replicate.
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Old 09-04-2019, 09:59 PM   #9
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Well last night I put everything back together, I did not see any corrosion on the connector, the alarm is on now so 12v to the ignition switch , tried to see if I could get the alarm to fail by moving wires around motor, but no luck. Still don't feel confident, I will try to check fuses, but electrical is working so loose connections are hard to replicate.
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Old 09-05-2019, 01:12 AM   #10
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Quote:
Originally Posted by Idaho_2700scr View Post
Well last night I put everything back together, I did not see any corrosion on the connector, the alarm is on now so 12v to the ignition switch , tried to see if I could get the alarm to fail by moving wires around motor, but no luck. Still don't feel confident, I will try to check fuses, but electrical is working so loose connections are hard to replicate.
Does the engine start now?

What do you mean the alarm is on, buzzes with key on but engine not started and stops once engine is running?
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Old 09-09-2019, 06:10 PM   #11
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This usually means the motor will start, I should have been more clear. The boat is in the my shop not in the water. I'm going to take it to the lake today or tomorrow to dump the black tank for the winter. I'm guessing the boat will start and run, I have not had it stop while running it has only not started when docked and tried to start. That is when I had no ac power to the switch, it could have been a loose connection at the 10 pin connector but I don't think so, the connector did not have any corrosion when inspected. I will have to see if it acts up again. thanks
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Old 09-11-2019, 03:50 AM   #12
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took the boat to the lake tonight, alarm was on this time and the engine would not start. This is the first time that I would not get the motor to turn over completely dead no cranking. Checked the ignition switch had 12.6 volts, checked the main 50 amp fuse on engine had 12.6 volts. Was hoping to get to the marina to pump out sewer and put boat away for the season, loaded up and brought it home. The normal way for starting my boat is when you turn the key the alarm goes off to tell you that you have oil pressure I guess, that you turn the key further to get the engine to crank and start.
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Old 09-11-2019, 12:34 PM   #13
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mmwjr

took the boat to the lake tonight, alarm was on this time and the engine would not start. This is the first time that I would not get the motor to turn over completely dead no cranking. Checked the ignition switch had 12.6 volts, checked the main 50 amp fuse on engine had 12.6 volts. Was hoping to get to the marina to pump out sewer and put boat away for the season, loaded up and brought it home. The normal way for starting my boat is when you turn the key the alarm goes off to tell you that you have oil pressure I guess, that you turn the key further to get the engine to crank and start.
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Since the alarm is sounding that mean there is 12V on the ignition switch I terminal. as you said the alarm sounds in test mode due to no oil pressure. Did the engine crank but not start or not crank? If it did not crank then you need to verify there is 12V on the ignition switch S terminal when the key is in the start position, Neutral safety switch is closed, slave solenoid is closing and delivering 12V to the starter solenoid. If cranking but not starting you need to verify if you have spark and fuel.
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Old 09-11-2019, 02:05 PM   #14
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Mike,
The motor would not crank, I only get the alarm now. I put my meter last night on the B terminal and had 12.6 volts. I also had 12.6 volts at the 50amp breaker on the engine. I will check the S terminal tonight when I get home.
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Old 09-11-2019, 04:51 PM   #15
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When trying to start check for voltage on the slave solenoid (number 1 in the pic) at its Red/Purple wire.

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Old 09-12-2019, 03:04 AM   #16
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Mike,
Checked the Terminal s on ignition switch 4.5 volts when tried to start, checked red and purple on slave solenoid no volts when trying to start.
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Old 09-12-2019, 12:27 PM   #17
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I would try the next either measure the ignition switch I terminal which you have 12V with the key in the run position to see if it drops voltage when the key is turned to the start position or use a jumper connected to the I terminal with the key in the run position and temporally touch the other end to the S terminal to see if the engine will crank over. If the latter works the ignition switch is bad. If in the first test the voltage on the I terminal drops you have either a weak battery or a bad connection somewhere in the system and will need to work backwards to find it such as does the voltage at the breaker drop when cranking.
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Old 09-12-2019, 03:13 PM   #18
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Mike,
I thought it was the ignition switch, I checked the voltage at the I position with the key in run position and had 4 volts, I replaced the ignition switch and still does not work (wont crank at all). I will check the voltage drop at the breaker, and continue to look for bad connection, thinking of replacing the slave solenoid.

Thank you
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Old 09-12-2019, 05:09 PM   #19
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Even without visible signs of corrosion on the 10 pin connector some have trouble with poor continuity through it. If voltage at the engine breaker stay at 12V when you are trying to start you should check for voltage drop across the 10 pin connector by using a pin or sewing needle to pierce the Red wire on either side of the connection so you can measure voltage at both locations when trying to start. if on the engine side you have 12V but the helm side get ~4V the connector is the issue.
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Old 09-18-2019, 04:02 AM   #20
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Mike,
I have checked voltage down to the starter and have consistent 12.6 volts, I'm going to take it in to a shop, guessing the neutral switch or solenoid on starter. Neutral switch is very hard to get to not sure if it is closing. thanks for your help
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