93 Johnson 150 - tilt/trim causing short - need guidance

[spencroy]

Short Version
Just purchased this boat, has not run in 5+ years.
Johnson 150 V6 - 1993 - Do not know the model yet.

When the connector for the tilt/trim to the front and comand center is connected at the motor, the main fuse by the celenoid blows when the key is turned to on.

If tilt/trim disconnected, the starter engages fine, the engine turn over, but wont quite run (almost as if starved for fuel).

My question - While troubleshooting, shouldnt the motor turn over and fire when starting even if tilt/trim is disconnected. If so I will open another thread for the probable fuel issues.

 

[spencroy]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

The Long Version:
I just got the boat, but this fourm has poven very helpful in the past, so I realize:

1. I need the shop manual. Right now I cant even figure out what model engine I have (there are like 30 in brp) any advice on how to first figure out what model I have, and then second advice on how/where to get a good manual (was not to pleased with my SELOC manual on my older boat)
--
Quick History
The boat sat for many years, I have tried to follow the steps in waking a sleeping outbord as much as possible.
- replaced lower unit oil
- replaced gas
- replaced main battery (all including trolls)
- replaced main battery cable to celenoid on the motor (both + and -)
- has a taddletail I think, so I can check the impeller if she ever fires

With all connections made, had all tilt/trim, had all gauges and lights working fine. When I would turn the key, the main fuse near the starter would blow

I struggled with it most of the day, then gave up and drilled the fourms here. Based on the suggestions I disconnected the tilt/trim at the engine.

At this point I had the following:
tilt/trim at the engine = working
tilt/trim on throttle/front = not working
Starter - working and the fuse does not blow. (engine wont fire, but hopefully unrelated problem)

If I plug back in tilt/trim, the fuse blows when I turn the key.

I assume this means that I have a short somewhere from the connector for the tilt/trim plug (male) at the motor forward to the dash and possibly ignition.

Working off this assumption I have found issues that cause me to question the integrity of this cable and I am struggling to determine in which wire the short exists (or how to find the correct replacement cable).

The connector (name?) for the tilt/trim at the motor at the plug has:
red/white - (to ground) 12v
blue/white
green/white
brown/tan
white/brown
Is the what I should expect from the plug (female) end of the connection?

I turned my attention to the cable run from the plug (male) down the cable, and found a short in the cable run. removed the short (by cutting section of the cable run and connecting them with inline connectors), but the problem persisted, removed the majority of the cable including sheathing, separated wires, could not find another short.

I have looked under the dash, but I have not cut all of those wires loose from the zip ties yet. When I trace the wires as good as I can by sight and hand it appears:
white/brown - connects to tilt/trim gague
brown/tan - connect to tilt/trim gauge
green/white blue/white and red/white - splits to front trim of boat and throttle trim (that is out of memory, will verify)

The wiring under the dash appears to be in good condition, no obvious place where the short is taking place.

The interesting thing to me is when I have a good fuse in, then tilt/trim work from the motor, the throttle, and front. However, when I turn the key on the fuse will typically blow, else it will blow when I turn her over.

Any suggestion for how to use the voltimeter to correctly identify which wire I should be focusing on as the culprit?

Thanks
Roy

 

[Chris1956]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Roy, Normally red/white is fused +12V. This would power the ign switch and PTT. It sounds like you have a short in the red/white wire, somewhere between the PTT connector and the control box. Look closely are the engine wiring harness as this is where the insulation is most likely to fail due to chafe.

Purple is usually Ignition Accessory(switched). if the fuse doesn't blow when the PTT harness is disconnected, ignition on, then this circuit is likely good. If the fuse blows with the PTT harness disconnected, look for melted or chafed purple wire at motor harness under dash where it connects to gauges.

You may have two shorted wires. Purple and red/white.

 

[daselbee]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

My books show the fused B+ wire color to be red/purple stripe. I don't see any red/white stripe wire listed...

 

[daselbee]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Re-reading, it seems as if you have the red/white T/T control wire shorted to the purple switched +12v wire inside the control box. This is assuming you have a control box with the ignition switch in the end.

 

[spencroy]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Thanks for the input so far. Let me try to add a couple of pics to clear things up a little.


The big pic:

The specifics of where I am seeing 12V in the Pt&t. If I understand power tilt/trim at all I would think that having 12V in the red/white wire is correct.

I swear I hate shorts, I am not very eletrically skilled at all. Basically at this point I am trying to confirm my short is not in the engine area and is somewhere forward

Any other pics that would help out let me know and I can upload them tonight.
Roy

 

[daselbee]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Yes...I understand your problem...
I have looked at the wiring diagram for the T/T system, and it appears that the red/white stripe wire at the T/T switch (forward, at the helm) does have +12v on it at all times.
The circuit follows as such: Batt +(at starter solenoid), to fuse via red wire, thru fuse, to ignition switch AND T/T junction box via red/purple wire, from j box to both the engine mounted T/T switch red wire AND the forward T/T switch red/white wire.

So, you have everything connected, and you key on, and the fuse blows.
THe only connections that are made internal to the key switch when key is ON is the one from B+ red/purple wire to the purple wire at the switch.
This is when key is ON. Only the two terminals with "B" and "I" on the back of the switch and with the colors I mentioned are connected inside the switch.

Try taking the purple wire off the back of the ignition switch. If your excessive load is coming from that purple wire, you will know.

Also, with no power on the circuit, measure with ohmmeter the purple wire to ground resistance.

I hope this is of some help.

 

[spencroy]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Good tip daselbee, thanks. I will try cutting the zip ties under the dash tonight and sorting out the purple wire. I take it then if I have the purple wire disconnected at the ignition switch (back) that I should show no volts, if I do then that is the line with my short. I hope that I am understanding correctly.

Thanks for the tip
Roy

 

[Fl_Richard]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

What if you pull the TT relay out of their sockets (on top of the #2 Carb). Maybe that will keep the fuse from blowing... allowing you to further your diagnostics.

 

[daselbee]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Pull the purple wire off the back of the ign. switch, turn key on, and I bet your fuse does not blow.
If you have 12v on that purple wire when disconnected, that is a problem, but it will not blow the fuse.
Fuse will blow with too much current in the circuit, like a short to ground, or any short that will cause excessive current flow. A +12v to +12v short will not cause any current flow.

Here is a helpful tip. Rig up a 12v automotive light bulb and wire it in in place of the fuse. Take fuse out, and insert wired up bulb...rig it up any way you want. The bulb will shine bright if a short exists, it will provide a load for the shorted circuit, and you will not be blowing fuses for each test. Note the brightness of the bulb, cause when you get it fixed, the bulb may still light up, just not as bright.

 

[spencroy]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Hello again..

Richard - I have disconnected the t&t relay, and the short no longer occurs (but I am not certain if that tells me the short is for sure from the t&t connection at the engine forward, or from the ignition (purple or perhaps yellow/red wire) back to the engine.

Daselbee - What a brilliant suggestion. I was so frustrated at the number of fuses I have blown while trying to figure this one out, and the answer of adding a light blub to the fuse is just one of those obvious things that I would never have thought of. Thanks so much for the tip.

To give a quick status update. I cut loose the majority of the zipties holding the wires behind the ignition last night. I was only able to work on the boat for about an hour, but in tracing the purple wire by hand/sight I have not yet found the blasted short. I will keep at her wire by wire till I finally find it.

I did order a OMC shop manual yesterday, that will end alot of my guess work as I think I have a pretty good understanding of the t&t circut, but I am convinced my short is actually in the ingintion circut and not the t&t, but I am just not certain (will be easier to trace when I have a firm grasp on the circuts on paper).

Thanks so much for the light suggestion and I will keep you posted on the results.
Roy

 

[spencroy]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

daslebee - your suggestion was the trick I needed. Following your advice I attached a small bulb between the fuses. I found that:
with the t&t relay unpluged
key off - no light
key on - dim light (1 in image)
key start - bright light (2 in image)

with the t&ft relay plugged in
key off - no light
key on - bright light
key start - bright light
[

Due to the previously mentioned cable integrity I had the luxury in this case of having the t&t cable severed and using your suggestion wire by wire found the cause of the short to be the black/tan wire running to the tilt/trim gauge on the dash.

There was not anywhere else in the cable run forward where i questioned the exterior cable integrity, and in examining the t&t gague from under the dash I could not see an obvious cause of the short. I removed the gauge from the dash and found the black/tan from t&t line laying on purple. Based on your advice (that the short was in purple as well) I made certain these two could not make contact and the short was resolved.

Thanks again for the tip on the light.
Roy

 

[daselbee]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Very glad you got it fixed. Shorts are tough.

 

[Riley C]

Re: 93 Johnson 150 - tilt/trim causing short - need guidance

Yes...I understand your problem...
I have looked at the wiring diagram for the T/T system, and it appears that the red/white stripe wire at the T/T switch (forward, at the helm) does have +12v on it at all times.
The circuit follows as such: Batt +(at starter solenoid), to fuse via red wire, thru fuse, to ignition switch AND T/T junction box via red/purple wire, from j box to both the engine mounted T/T switch red wire AND the forward T/T switch red/white wire.

So, you have everything connected, and you key on, and the fuse blows.
THe only connections that are made internal to the key switch when key is ON is the one from B+ red/purple wire to the purple wire at the switch.
This is when key is ON. Only the two terminals with "B" and "I" on the back of the switch and with the colors I mentioned are connected inside the switch.

Try taking the purple wire off the back of the ignition switch. If your excessive load is coming from that purple wire, you will know.

Also, with no power on the circuit, measure with ohmmeter the purple wire to ground resistance.

I hope this is of some help.

Dasel,

Im having the same issue with my 87 140 Looper. The starter won’t turn and the solonoid buzzes when turning it on. It’s only when I disconnect the red/white 12v and the trim switch cable does the engine turn.

Please help!

 

[GA_Boater]

Dasel,

Im having the same issue with my 87 140 Looper. The starter won’t turn and the solonoid buzzes when turning it on. It’s only when I disconnect the red/white 12v and the trim switch cable does the engine turn.

Please help!

Please start a new thread of your own. This one has been in the basement resting for over ten years.

Closed.