Battery Sparking when re-connecting cables? - Diesel Forum

rrock33 · 08-09-2005, 07:22 AM

I am a new working on trucks let alone diesel engines. I did some work on my '93 Ford F-350 and the repair manual I have told me to disconnect the negative cables from both of my batteries before starting any work. I left the positive cables connected. So I did that and completed my work. I went to reconnect the passenger side negative battery cable and I heard clicking sound from the engine. I didnt tighten it down yet. I then went to connect the driver side battery cable and I got lots of sparking once I made contact with the terminal. Out of surprise I let go of the cable and it is resting on the terminal. Not knowing what to do I removed the passenger side cable. I then tried the remove the drivers side cable so that I would be back a square one with both cables disconnected and heard lots of clickig(starter motor?) and the truck lurched a little forward(it was in gear at the time)! So as of now passenger side negative cable is disconnected and driver side negative cable is resting on the terminal.

ANY ADVICE ON HOW GET THE CABLES HOOKED WOULD BE GREATLY APRRECIATED. I am little "gun shy" on doing anything until I get some advice.

mateo · 08-09-2005, 08:28 AM

I'd check the connections on the starter relay, located on the passenger's fender. They're cheap to replace too.

cdnsarguy · 08-09-2005, 08:42 AM

What work did you do..........

First I would put it in nuetral, ensure the key is off and disconnect the negative cable that is hooked up so that both are disconnected until you/we can get to the bottom of the problem.

There should be no major power sparking, there will be a small spark as some items will be using battery power ie the radio and any door/hood lights if open.

rrock33 · 08-09-2005, 12:39 PM

Thanks for your respnoses. I did put thr truck in neutral. I did have to re-land a wire that was connected to a plastic "black knob" looking device(is this what you meant) on the inside of the passenger side fender. The stud that had been holding this wire down came had corroded and broke loose. I re-landed this wire without any thought on the other terminal of this "black knob" device which had many other wires going to it. If this is the problem am I safe loosening the nut off and pulling this wire back off? If when will I then be able to remove negative battery cable on the drivers side battery without the sparking I mentioned?

tim94f250 · 08-09-2005, 01:44 PM

This "Black Knob" you speak of, does it have two studs that are the same size? I think you are talking about the starter relay. If it is all corroded, that is what may have made your truck lurch foward when you connected your battery grounds. If you could post a pic, that would help.

rrock33 · 08-09-2005, 02:39 PM

I will post a pic tomorrow. Thanks.

comp486 · 08-10-2005, 12:11 AM

that is your starter relay. the wire you moved has to be on the post it was on before you moved it! by moving it you put power to your starter solenoid all the time, just like holding the key in the start position [img]/ubbthreads/images/graemlins/eek.gif[/img]. go to your parts house and get a new starter relay and clean all the wires and reconnect like on the old one. some anti ox on the terminals will help also. [img]/ubbthreads/images/graemlins/smokin.gif[/img] [img]/ubbthreads/images/graemlins/smokin.gif[/img] Jeff

rrock33 · 08-10-2005, 11:16 AM

Thanks for all your repsonses. You are all right...it is the starter relay. I looked it up in my repair manual and thats what is looks like. As "jeffdrobison" notes that must be why the truck lurched a little forward because I have essentially bypassed the start circuit in my ignorance.

Next Question: I need to re-land that one wire back to where it was on the starter relay and disconnect my drivers side negative battery cable to get back to square one. I dont want to repeat this lurching forward again so my question is in what order do I disconnect/reconnect these cables and wires without having that problem again? Note: currently my passenger side negative battery cable is disconnected and the drivers side negative battery cable is "connected"(really resting on the terminal). Both positive battery cables are connected. Thanks.

tim94f250 · 08-10-2005, 05:24 PM

Make sure both negative cables are disconnected. Then remove the wires from the starter relay. Remove and replace the starter relay on the inner fender. Connect the wires on the starter relay and tighten. Now, with the truck in park or neutral and the brake set, reconnect the negative battery cables. You should now be able to start your truck. Tim

rrock33 · 08-10-2005, 06:14 PM

The last time I tried to remove the negative cable from the drivers side battery I get all kinds of sparks, I hear the starter motor clicking, and the truck lurched forward. I released the cable when this occurred and it is now resting on the terminal. I have put the truck in neutral now. Wont the same thing occur though with the starter motor trying to start?

tim94f250 · 08-10-2005, 06:36 PM

Once you have the negative cables disconnected, nothing can happen. Make sure both are disconnected, then switch out the relay. Tighten the wires on the relay, then connect the negative cables.

I just went to my truck to see how many wires are on each relay terminal. On the terminal torwards the front of the truck, there should be one red wire connected. On the terminal torwards the back of the truck, there should be one heavy gauge red wire, and three sets of two wires, two are light green, and one is orange. I hope this helps

rrock33 · 08-10-2005, 06:50 PM

So I shouldn't worry about the sparking that will occur or the starter motor trying to start when I got lift the negative cable off the drivers side battery? I was hoping there might be a way to do this without that happening.

tim94f250 · 08-10-2005, 06:54 PM

Make sure that your key is in the off position. Take that wire off of the relay that you moved. The battery terminal will have very minor arching.

westbound · 08-12-2005, 11:36 PM

as i discovered today, major arcing (direct short to ground) is a scary thing. a lot like my lincoln arc welder at 75 A. if this happens when you connect your terminal something is wrong. if its a little arc you can barely see or hear, that's normal.

rrock33 · 08-13-2005, 02:39 PM

Tim - When I try to take wire off of the relay I started to get some sparking just by loosening the nut. So I am still at a point where if I try to remove this wire or the negative battery cable from the drivers side battery(passenger side battery neg cable already discoonnected) I get sparking.

Does anyone a good electrical diagram of a '93 Ford F-350 IDI?