[michaelanderson]

I got trapped in a flash flood the other night, crossed a few areas of running water 1 foot deep with no trouble. When I went through the 4th area my engine suddenly quit. I got out and the water was about 2 inches below the door. I pushed the car back about 30ft to get it to higher ground. Checked the air cleaner and it was bone dry, top of engine never got wet, distributor and all was dry. The car will crank but not start. The 3 or 4 big fuses in the engine bay look fine.

Also, when it first died I pressed the hazard switch on top of the steering column. Smoke start rising from the switch so I turned it back off. I discovered that the 15A fuse for the Engine light and other dash lights is blown. It blows a new fuse as soon as the ignition is turned on. I'm not sure if this is related or is a separate problem as I've never used the hazard before.

The car has been sitting for 2 days and should be pretty dry now but still will not fire. I have not tried to replace the 15A fuse again yet, not sure if that would keep the car from starting. Where should I look next to troubleshoot this? Thanks.

 

[fordem]

Which 15A fuse, for which engine light and which other dash lights? There is no fuse specific to dash lights, unless you're referring to the gauge lighting and that fuse also powers the park lights.
Be specific - if it's related to the ignition or fuel injection system (which I suspect it is) the car won't run without it - it's also unlikely that any amount of "drying out" will solve the issue.

The hazard lights are not fed via the ignition switch so the two symptoms are unrelated.

If the fuse blows again, try unplugging the alternator connector and then replacing the fuse again - a foot of water is not a significant amount, but if you splash enough it can get onto drive belts and that throws it around quite a bit.

 

[xkaes]

I got trapped in a flash flood the other night, crossed a few areas of running water 1 foot deep with no trouble.

Just guessing here -- Las Vegas?

 

[michaelanderson]

Sorry, I had found a diagram on my phone that indicated that this fuse controlled the dash lights. It is the one circled in red. The fuse below it is empty because I borrowed that one to test the circled one. I will hopefully get a chance to work on this tomorrow.

Which 15A fuse, for which engine light and which other dash lights? There is no fuse specific to dash lights, unless you're referring to the gauge lighting and that fuse also powers the park lights.
Be specific - if it's related to the ignition or fuel injection system (which I suspect it is) the car won't run without it - it's also unlikely that any amount of "drying out" will solve the issue.

The hazard lights are not fed via the ignition switch so the two symptoms are unrelated.

If the fuse blows again, try unplugging the alternator connector and then replacing the fuse again - a foot of water is not a significant amount, but if you splash enough it can get onto drive belts and that throws it around quite a bit.

 

[michaelanderson]

Not in Vegas but nearby. We did have some fatalities here. We went from no rain at all to completely impassable roads in 5-10 minutes because of the flash flooding. See attached video. Oops can't attach a video here.

Just guessing here -- Las Vegas?

 

[Johnz12321]

Pretty sure there's an important harness that controls fuel pump and stuff that runs under/behind the plastic trim just below the drivers door all the way to behind the drivers side tail light, I would check to make sure it didn't get soaked and shorted out.

 

[Bex]

I believe that the fuse that you’ve blown is the ignition coil fuse, and if so, yes, the dash lights will not work, and the engine will only crank. The ignition coil fuse runs quite a bit of the car: fuel pump relay, alternator, ignition coil, instrument gauges and lamps, main relay, noise suppressor, O2 heater, etc.
As Fordem says, splashing creates problems (I often have to go through a foot of water, and do so while attempting not to create any kind of ‘wake’ or splash with the tires). I’d probably start with the alternator, and see, as per Fordem’s suggestion, if with the alternator connector disconnected, if the fuse still blows with the ignition on. At some point, rather than going through a box of fuses, you may want to replace the fuse with a test light. The light will be lit, indicating a short somewhere. Then start disconnecting each of the connectors to the items that are on that circuit, to see where the short is located….the light will go out when you disconnect the right one.

 

[fordem]

Sorry, I had found a diagram on my phone that indicated that this fuse controlled the dash lights. It is the one circled in red. The fuse below it is empty because I borrowed that one to test the circled one. I will hopefully get a chance to work on this tomorrow.

There is something I need you to understand - the term "dash lights" is not specific - charge light, oil pressure light, high beam light, turn signals - they are all dash lights, and of the four I mentioned (there are others) three different fuses are involved.

As Bex has said, that appears to be the IG/COIL/METER fuse, so, not dash lights, but if it's blown there will be no power to the ignition system and that will include things like the charge & oil pressure lights. Amongst the things that that fuse will supply power to is the alternator, and the reason I suggested that you disconnect that early in the troubleshooting process, is that there are exposed (not protected by insulation) connections inside there, that can get wet. It may not be that, but it's just one plug to unplug.

Pretty sure there's an important harness that controls fuel pump and stuff that runs under/behind the plastic trim just below the drivers door all the way to behind the drivers side tail light, I would check to make sure it didn't get soaked and shorted out.

Electrical wiring, on a motor vehicle, does not "short out" simply because it gets wet - each individual wire is enclosed in a plastic (typically PVC) jacket which is more or less waterproof - many, many vehicles have exposed wiring under the vehicle, outside of the passenger cabin, in the engine compartment, and all exposed to the weather - I routinely drive through water, maybe not as much as a foot deep, but I've had vehicles fill to the bottom edge of the doors and sit with that water in there for days and never had an issue with the wiring. One of my 4WDs has an electronically shifted automatic transmission (these are now quite common), the transmission harness exits the passenger cabin through a a rubber seal in the floor under the driver's seat - it gets wet every time that vehicle is in water - this is how it was designed to work.

Unless there has been physical damage to the harness, getting it wet will not cause it to "short out".

 

[michaelanderson]

Thanks, I will look for this harness this morning.

Pretty sure there's an important harness that controls fuel pump and stuff that runs under/behind the plastic trim just below the drivers door all the way to behind the drivers side tail light, I would check to make sure it didn't get soaked and shorted out.

 

[michaelanderson]

Thanks, I'll try the alternator first.

I believe that the fuse that you’ve blown is the ignition coil fuse, and if so, yes, the dash lights will not work, and the engine will only crank. The ignition coil fuse runs quite a bit of the car: fuel pump relay, alternator, ignition coil, instrument gauges and lamps, main relay, noise suppressor, O2 heater, etc.
As Fordem says, splashing creates problems (I often have to go through a foot of water, and do so while attempting not to create any kind of ‘wake’ or splash with the tires). I’d probably start with the alternator, and see, as per Fordem’s suggestion, if with the alternator connector disconnected, if the fuse still blows with the ignition on. At some point, rather than going through a box of fuses, you may want to replace the fuse with a test light. The light will be lit, indicating a short somewhere. Then start disconnecting each of the connectors to the items that are on that circuit, to see where the short is located….the light will go out when you disconnect the right one.

 

[michaelanderson]

The dash lights I was referring to were the check engine lights and others that illuminate with the key is turned on. When I turn the key, I currently get no light on the dash at all.

The last harness I worked on was for the AC. When I tried to pull it apart both sides of the plastic harness disintegrated in my fingers. The plastic had almost turned to dust. I would not be surprised if some of the other harnesses on the car were in similar shape and may not longer be waterproof. I'll look for the one under the door area after I check the alternator.

There is something I need you to understand - the term "dash lights" is not specific - charge light, oil pressure light, high beam light, turn signals - they are all dash lights, and of the four I mentioned (there are others) three different fuses are involved.

As Bex has said, that appears to be the IG/COIL/METER fuse, so, not dash lights, but if it's blown there will be no power to the ignition system and that will include things like the charge & oil pressure lights. Amongst the things that that fuse will supply power to is the alternator, and the reason I suggested that you disconnect that early in the troubleshooting process, is that there are exposed (not protected by insulation) connections inside there, that can get wet. It may not be that, but it's just one plug to unplug.



Electrical wiring, on a motor vehicle, does not "short out" simply because it gets wet - each individual wire is enclosed in a plastic (typically PVC) jacket which is more or less waterproof - many, many vehicles have exposed wiring under the vehicle, outside of the passenger cabin, in the engine compartment, and all exposed to the weather - I routinely drive through water, maybe not as much as a foot deep, but I've had vehicles fill to the bottom edge of the doors and sit with that water in there for days and never had an issue with the wiring. One of my 4WDs has an electronically shifted automatic transmission (these are now quite common), the transmission harness exits the passenger cabin through a a rubber seal in the floor under the driver's seat - it gets wet every time that vehicle is in water - this is how it was designed to work.

Unless there has been physical damage to the harness, getting it wet will not cause it to "short out".

 

[xkaes]

I have the same problem with 30+ year old plastic connectors -- but the 30+ year old wire covering can disintegrate too. I find that getting the 30+ year old dirt off is the biggest challenge.

 

[Bex]

You might notice that a lot of the harness damage is on the underside of the harness, where it has been rubbing against metal brackets, etc., for years, so some of the deterioration is not easily seen.

 

[fmartin_gila]

At some point, rather than going through a box of fuses, you may want to replace the fuse with a test light. The light will be lit, indicating a short somewhere. Then start disconnecting each of the connectors to the items that are on that circuit, to see where the short is located….the light will go out when you disconnect the right one.

Excellent way to chase shorts but I use a piezo buzzer instead of a light bulb to jump across the fuse terminals and you can go about testing without constantly having to watch the light. I have used this method for many years while diagnosing shorts. The buzzer will buzz as long as the short exists but will limit the amount of current flow to what the buzzer needs so will not hurt the wiring.

Fred

 

[Chrissybabe88!]

Note that water does not short out 12v cables or plugs by itself. At least to the extent that it will blow a fuse. The presence of corrosion in contact pins after repeated exposure to water will though because the corrosion byproducts are conductive. Water can affect analog signals present in the cable but still typically doesn't blow fuses. So if your vehicle was working okay, enters water and then blows a fuse it is more likely caused by physical damage from the water rather than electrical damage. eg water pressure could cause the collapse of a plug housing thus allowing one or more of the pins to short out - that will blow fuses.
When a vehicle is designed one of the decisions made is what to make the plug housings from. $5 for xyz material and that is known to last minimum 10 years or $20 for abc material known to have a lifetime of 30 years. You can guess which they chose. This is an over simplification but the principles hold (the injector plug housings of a 300zx which fail early from the heat soak in the engine - they used a plastic which does not handle heat as well but was chosen because it was cheaper).

 

[Johnz12321]

Electrical wiring, on a motor vehicle, does not "short out" simply because it gets wet - each individual wire is enclosed in a plastic (typically PVC)

Unless there has been physical damage to the harness, getting it wet will not cause it to "short out".

I should've specified: in my experience living in the rust belt, excess water has 100% been the cause of shorts on 3 separate trackers, 2 bad, 1 good. The shield around the wires is over 30 years old now, and is compromised on most of my trackers that didn't live down south. One of them the entire wiring to the back under the door was wet on the inside and they were all green inside the pvc outercoat, which would blow the IG fuse whenever it went through deep enough water to touch the bottom of the door. The other was when it would rain, because the wheelwell had rusted through, the tire would kick water to the plug connector behind the taillight, and blow the IG fuse. Another one still to this day, the dome light will only turn on when it rains, a rusted ground makes connection when it's wet, completing the circuit and it works.