520 H won't start. Hour meter/oil sensor

[608KEB 794]

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Edited August 22, 2015 by 608KEB

[608KEB 794]

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Edited August 22, 2015 by 608KEB

[Save Old Iron 1,563]

the 15 amp fuse powers the headlights only

the 30 amp fuse is for charging the battery

neither of these will cause a cranking problem

[608KEB 794]

I picked up 6/12 tester. The 15 amp fuse was blown! I replaced all the fuses when I started this project. I overlooked the fuses after replacing them. I still have the oil warning light not working. I can look at that again. I'm just happy it was something simple. All three fuses have around 12.5 volts.

I'm confused. I just pulled the 15 amp out and it wouldn't start. Put it back in and it started. It won't start with the 25 amp pulled out either. 

Edited August 22, 2015 by 608KEB

[Save Old Iron 1,563]

let me look again at the wiring diagram

the 15 amp fuse powers the headlights only

the 30 amp fuse is for charging the battery

neither of these will cause a cranking problem

slight correction for the 520

the 15 amp fuse controls the lights, gauge power and indicator pod power.

I see no apparent connection withe the 15 amp circuit and the engine cranking or running.

With the 15 amp fuse removed, if the engine will not start , will it still CRANK?

[squonk 38,928]

Maybe pulling the fuses made a bad connection in the block better and allowed it to start by closing a safty circuit?

Edited August 22, 2015 by squonk

[cheesegrader 433]

I agree with squonk.
That fuse block is a piece of junk.
I think you have an intermitent short at the block, and every time you work on it, you change the problem.
(In addition to the reversed sensor wires, which appears to be solved now)
I would cut the %&$##$%! thing out and replace with three individual sealed auto fuse holders.
I've been amazed at the problems that I have solved just replacing that thing.

[608KEB 794]

It wouldn't crank over with the 15 amp fuse out. I"ll change the fuse holder and report back. Cheese grader do you have a picture you could post of your upgraded fuse block?

Edited August 23, 2015 by 608KEB

[Save Old Iron 1,563]

It wouldn't crank over with the 15 amp fuse out. I"ll change the fuse holder and report back. Cheese grader do you have a picture you could post of your upgraded fuse block?

Interesting. Maybe someone with a similar year 520 could post a quick picture of what amperage fuse goes in which fuse block position. I'm curious if the 15 and 25 amp fuses are swapped. The no start / no crank symptoms are 25 amp position related. If there is a 15 amp fuse in the 25 amp circuit... this could account for the 15 amp fuse blowing out as you have mentioned earlier. Flipping the fuse holder over and checking the colors of the wiring should give some clue.

[608KEB 794]

When I get time I'll take the fuse block out. Both the 15 and 25 amp fuse had to be connected in order for it to start.

Edited August 23, 2015 by 608KEB

[cheesegrader 433]

The first picture is a 96 with the original fuse block still in place.
Fuse order, back to front, is 30/25/15

The second picture is a 94 with the block out and individual holders in (without the velcro straps holding them)
30 is red/red 
25 is 2 white/orange
15 is whatever was left, can't remember

The third picture is the reason the 94 block failed.  Yuk!

[Save Old Iron 1,563]

Make sure the fuses are in the correct slots.

[608KEB 794]

I have my 15 and 30 amp in the wrong slots. On my 93 520 the 15 amp is closest to the seat. I just checked. I pulled the 15 amp out of the 93 and the lights went out. On the 94 I'm working on the 30 amp is closest to the seat. I just checked that too.

Edited August 23, 2015 by 608KEB

[Save Old Iron 1,563]

another issue resolved, this is why the 15 amp fuse was intermittently blowing.

We took a few detours in the last day or two.

What works and what still needs fixin?

Edited August 23, 2015 by Save Old Iron

[608KEB 794]

The oil sensor light still does not come on when I turn the key to start. I will be home Friday to look into it further.

[Save Old Iron 1,563]

one terminal on the pressure switch should be grounded with withe engine OFF - hook the oil pressure indicator to that terminal.

the second terminal on the pressure switch should ground out WHEN THE ENGINE IS RUNNING / HAS OIL PRESSURE - connect the hour meter to this switch terminal.

we need to go back and check for proper operation of the pressure switch by using the resistance range on the multimeter

engine off  -  no wires connected to pressure switch - multimeter set to 200 ohms range - measure from the metal switch body to each terminal

one terminal should show a near 0 ohms reading, the other should show an open (over range) reading

start the engine - the two wiring terminals on the pressure switch should REVERSE their resistance readings - 0 ohms should go over range - over range should now read near 0 ohms

simply put, the two screw terminals on he switch should never have the same resistance value  engine on or engine off

let's get these switch conditions verified before going any further.
 

 

Edited August 24, 2015 by Save Old Iron

[Horse Newbie 6,859]

@608KEB, did you ever get this oil pressure switch wired up ?

[Horse Newbie 6,859]

Also... @608KEB where did you get the OEM part ?

On 8/24/2015 at 2:54 AM, Save Old Iron said:

we need to go back and check for proper operation of the pressure switch by using the resistance range on the multimeter
engine off  -  no wires connected to pressure switch - multimeter set to 200 ohms range - measure from the metal switch body to each terminal

one terminal should show a near 0 ohms reading, the other should show an open (over range) reading

start the engine - the two wiring terminals on the pressure switch should REVERSE their resistance readings - 0 ohms should go over range - over range should now read near 0 ohms

simply put, the two screw terminals on he switch should never have the same resistance value  engine on or engine off

let's get these switch conditions verified before going any further.