# Ford 550 TLB - turn the key and...nothing :(



## 8990TRAC (Jun 16, 2013)

Hello,

another day, another new problem...

I've just fitted a new set of instruments to my digger, so I can have a working tachometer. In the process, I've had to guess where most of the wires went, as the old instruments have a completely different back to the new instruments and the 550/555 manuals are nothing like either of them...

I've been turning the electrics on and off all morning and had finally got the right wires to the right lights at least, had started it two or three times and everything was fine.

The last job was to connect up the tacho cable, which, it turns out, is only just long enough to get about one turn on either screw-lock at the ends. Once that was connected, I went to start it and...nothing. A sort of "clunk" from the starter and all the lights went out.

I turned the key off and on again (fixing technique no. 1) and still no lights; then, with the key in the on position for about ten seconds, the battery and oil pressure light pinged back on (full brightness) and some relay behind the dash somewhere switched with a clonk.

I tried starting it again - same thing. This time, the battery light was very very dim for about ten seconds before it and the oil pressure light came back to full brightness.

I've checked the battery terminals and they're good - I'm pretty certain I've not disturbed any of the wiring behind the dash and, even if I've got a couple of wires wrong on the instruments, they're only instruments, so shouldn't stop the engine from turning over, surely?!

Any thoughts would be much appreciated - I had all the same symptoms as this once before and it was a bad positive battery cable (corroded through at the battery end), but I replaced that weeks ago and it's been fine since then. The battery's brand new, although I've not checked the voltage on it - it started the digger fine a couple of hours ago and the engine turned over fine, not slow or laboured at all.

I'm thinking some sort of bad relay somewhere in the starter circuit, but I don't know if there even is one - I doubt it, as the wiring's about as a simple as you can get away with on a tractor/digger, really...

Thanks for your help 

p.s. A while ago, I asked about a leaking hydraulic hose under the backhoe - people asked at the time to let them know how it went...sorry about that! I tried to tighten it, but it was absolutely solid and I didn't want to shear the connector or anything, so I've attached a picture of my engineering solution......no more oil on the ground


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## 8990TRAC (Jun 16, 2013)

Right - a bit more investigation and I have some pretty specific symptoms, but still no real idea what the problem is.

With the ignition off, the battery is at 12.65V.

When I turn the ignition on, one of two things happens;
1) Momentary drop in Voltage to about 12.30V
2) Relay clicks behind dash
3) Voltage raises to about 12.50V
4) Battery and Oil light come on bright
...or...
1) Voltage drops to about 3.30V
2) No relay click behind the dash
3) Voltage gradually raises to about 5.50V (I turn it off at that point)
4) Battery and Oil light on very dim

When I try to start the engine, what happens depends on the Voltage:
System at 12.50V;
1) Voltage drops to about 3.50V
2) Simultaneous "clonk" from the starter
3) Voltage returns fairly quickly (2 seconds) to 12.50V when I release the key
...or...
System at 3.30V or thereabouts;
1) Voltage drops to around 1.50V
2) No sound from starter
3) Voltage returns to 3.50V and slowly rises when I release the key

...so, er...well, I haven't got a clue. My best guess is that the starter's jammed and the starter solenoid is sticking sometimes. I'd try rocking it in gear to see if the starter un-jams, but the backhoe and the loader are on the ground, so I can't move it...

I haven't tried the old hitting-the-starter-with-a-hammer trick yet, but any thoughts from wiser heads would be welcome. Something's obviously drawing a huge current to drop the battery voltage that much - I'm pretty certain it doesn't have glow-plugs, but I can't think what else (other than the starter) could draw that much current...

Thanks for your help


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## 8990TRAC (Jun 16, 2013)

Right (again) - I went out and performed the old hit-the-starter-with-a-hammer trick and, what do you know, it started fine.

I'm not convinced my hitting it with a hammer was the fix, though - normally I'd get somebody else to turn the key while I hit it (or the other way round, for variety), but there's only me, so I was doing the hitting and the starting, which I don't think really works.

There's definitely something not right, but like most problems, it'll either go away or get worse (and more obvious what the cause is)...

I'm still open to any suggestions


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## FredM (Nov 18, 2015)

first thing i would be doing -- remove both positive and negative battery connections and clean the battery posts and cable connectors, then remove the earth connection at the chassis and clean that, and then clean the connection at the solenoid post where the battery cable connects.
battery posts and connectors grow a residue where they connect and this will do what you describe, the battery posts have to be lead shiny and same for inside the battery post clamps, also check and clean the connections on the supply cable that goes from the solenoid post to the dash console.


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