88 Merc 135 keyswitch short no spark

[downsideup]

I have an 88 Sea Ray branded Merc 135. I get no spark unless I disconnect the black/yellow killswitch wire from the switchbox. According to what I remember from my last Merc manual (it went with my last boat and I'm waiting delivery of a new one) this indicates a short in the harness or keyswitch. I replaced the keyswitch and I have the same problem. Any advice on how to track down a short in the harness? Just for the record, the harness looks to be in good condition ie: not frayed or taped or messed with.

Any insight is greatly appreciated. This forum has been great for me!

 

[j_martin]

Re: 88 Merc 135 keyswitch short no spark

I have an 88 Sea Ray branded Merc 135. I get no spark unless I disconnect the black/yellow killswitch wire from the switchbox. According to what I remember from my last Merc manual (it went with my last boat and I'm waiting delivery of a new one) this indicates a short in the harness or keyswitch. I replaced the keyswitch and I have the same problem. Any advice on how to track down a short in the harness? Just for the record, the harness looks to be in good condition ie: not frayed or taped or messed with.

Any insight is greatly appreciated. This forum has been great for me!

The toggle switch under the key is also connected to that. It is arranged so a lanyard with a loop on it is put over the switch, when the lanyard is pulled, it'll snap the switch down and kill the engine.

There is probably a mercury tilt switch on the engine in that same circuit.

That, and a mouse bite on the harness are your options.

hope it helps
John

 

[sschefer]

Re: 88 Merc 135 keyswitch short no spark

I have an 88 Sea Ray branded Merc 135. I get no spark unless I disconnect the black/yellow killswitch wire from the switchbox. According to what I remember from my last Merc manual (it went with my last boat and I'm waiting delivery of a new one) this indicates a short in the harness or keyswitch. I replaced the keyswitch and I have the same problem. Any advice on how to track down a short in the harness? Just for the record, the harness looks to be in good condition ie: not frayed or taped or messed with.

Any insight is greatly appreciated. This forum has been great for me!

While it could be in the key switch, it could also be in the safety switch. This is a really easy circuit to test because it's all ground. The primary wire color of black tells you that it's ground and the secondary color of yellow tells you it's ignition. All you need is a cheap multimeter to check if the path to ground is open or closed. Open it will run, closed it won't.

When looking at the meter, 0 movement or 0 ohms means it's shorted or a closed circuit. Movement fully to the right or a reading of 30,000 ohms or greater means infinite resistance or an open circuit.

At the switch box, remove the black/yellow wires from the switch box terminal.

With the safety lanyard correctly inserted into the safety switch and the key in the off position, check for a closed circuit between the two terminals with black and yellow wires on them. If it's closed, replace the safety switch, if it's open then connect one lead of the multi meter to ground and the other to either terminal. With the ignition key off, one terminal should read closed circuit and the other should read open circuit.

If both read closed circuit then the problem is in the wiring harness so disconnect the plug at the engine between the engine and the ignition switch. If it's still closed then that's where your problem is. If it's open then the problem is a short and it's probably the mercury (meaning heavy metal) switch that is inline with the black/yellow wire at the switchbox. You can start at either end of the boat with these tests.

 

[downsideup]

Re: 88 Merc 135 keyswitch short no spark

Wow! 2 instant replies and both insightful. Thank you! Problem is...I don't think there's a lanyard/safety switch. This boat is new to me (1 week) but the previous owner didn't say anything about a lanyard. A simple key on a floating fob was all that was supplied. Nothing else. That being said, sschefer's method of tracking down the short is concise and easy to follow. I have a multimeter and will get on that asap....oh and I'll look for a safety switch somewhere....If I find one I'll feel like a fool. At least I'll be a fool with a running outboard

I'll post my results and maybe someone else can benefit from my experience (or stupidity)

Thanks guys....again....this forum is amazing.....I recommend it to anyone with a boat.

 

[sschefer]

Re: 88 Merc 135 keyswitch short no spark

Wow! 2 instant replies and both insightful. Thank you! Problem is...I don't think there's a lanyard/safety switch. This boat is new to me (1 week) but the previous owner didn't say anything about a lanyard. A simple key on a floating fob was all that was supplied. Nothing else. That being said, sschefer's method of tracking down the short is concise and easy to follow. I have a multimeter and will get on that asap....oh and I'll look for a safety switch somewhere....If I find one I'll feel like a fool. At least I'll be a fool with a running outboard

I'll post my results and maybe someone else can benefit from my experience (or stupidity)

Thanks guys....again....this forum is amazing.....I recommend it to anyone with a boat.

It's supposed to have a red top and will look like a button switch but the lanyard piece actually lifts it and holds it out. If it's been broken off it may look like a reset button or something on that order. It could be on the dash or the controls.

 

[j_martin]

Re: 88 Merc 135 keyswitch short no spark

Look at the control set just below the key switch. If there's a toggle switch there, it's the kill switch. It needs to be in the up position for spark.

There is a lanyard that goes under the handle in such a way that when the lanyard leaves, it throws the switch down.

Anyway, that's the way my 1988 v6 is rigged.

hope it helps
John

 

[sschefer]

Re: 88 Merc 135 keyswitch short no spark

Look at the control set just below the key switch. If there's a toggle switch there, it's the kill switch. It needs to be in the up position for spark.

There is a lanyard that goes under the handle in such a way that when the lanyard leaves, it throws the switch down.

Anyway, that's the way my 1988 v6 is rigged.

hope it helps
John

I just saw one of those setups on the Bayliner I pulled the V135 off of. I'd never seen it done that way before.