Confunding electrical problem, 1999 Volvo 5.0GL PWTR

[craze1cars]

Had my dash cluster loose yesterday, probing around with a meter to figure out why my voltage drop seems a bit excessive at the dash...but everything was running fine...voltage gauge reads about 11 at the dash.

With ignition ON, I put multimeter probes on "ign" and ground probes on the back of the volt meter. I accidentally shorted the two and was greeted with a very tiny little quick spark and the entire dash panel went dead. Oops.

I dove under the dash and immediately found a blown 5 amp fuse in the "ignition" slot. This looked like a little 5 amp spark to me. So I replaced it. While there I verified 12.6 volts at both sides of this fuse. Figured I was done.

So I went back up top and turned ignition switch back on. Nothing.

With ignition switch OFF, I have 12.6 volts when I put meter between the "B" (hot) probe of the ignition switch, and ground on the back of the volt meter. But as soon as I turn the ignition switch to ON, the voltage drops to ZERO. I cannot figure out why. When I move the red probe over to the "I" slot of the ignition switch, I still get zero volts. So now I'm thinking maybe I somehow shorted out the ignition switch?

I have removed the ignition switch and tested it for continuity. It is fine, and switches on and off like it should at the 3 terminals. I even temporarily installed it in my other boat and it fired right up no problem. So the ignition switch is fine. But I can't get 12 volts to go through it to turn on power to the ignition circuit on this boat.

I ran a jumper wire straight from the battery and touched + to the "I" terminal on the voltage gauge, and - to the ground on the same gauge. This energized the ignition circuit as it should. Yet I can't get it to work through the ignition switch despite reading a solid 12.6 volts right there at the hot terminal of the switch itself. And why does that number drop to zero the moment I turn the ignition switch on?

What the heck am I overlooking here? Very confused. Thanks for any suggestions for solutions or further troubleshooting methods if you have them.

 

[Bt Doctur]

Re: Confunding electrical problem, 1999 Volvo 5.0GL PWTR

thats the trouble with voltmeters, they cant produce a current flow. Try putting the + jumper to the main feed on the switch. If it works .you could have a corrosion issue with the wire that supplies + voltage to the switch.

 

[Don S]

Re: Confunding electrical problem, 1999 Volvo 5.0GL PWTR

Is this "dash cluster" one of those 1 piece things with printed circuit boards and all, or just a panel with some gauges attached with wireing to normal gauges.
If you have power, then loose it when you turn the ign. sw. on, then you have a bad connection somewhere. Either positive or negative.

 

[craze1cars]

Re: Confunding electrical problem, 1999 Volvo 5.0GL PWTR

Yep. found it. Is not actually a cluster with printed boards...just a bunch of individual guages.

Thanks for the "second eye" bt doctur. I did what you said. The jumper straight to the hot on the ignition switch lit everything up just fine. So I then knew I had a problem on the HOT side of things. So I just turned the ignition on so voltage went to zero at the switch, then systematically used my meter and probed my way closer and closer to the switch along all hot connections until I lost the voltage....right there at the fuse block. Wiggled things around there and blippity blip...everthing lit up! So Don S, you were likewise correct...had a bad connection. I just had a little difficulty thinking thru how to best trace it.

Fixed that connection and all is back to "normal" now. Thanks to both!

________________________________________________________

So...NOW back to the original problem I was originally tracing before I created the problem above...excessive voltage drop. So someone please tell me if this is normal:

With ignition off, I get 12.6 volts at the ignition switch. AND 12.6 volts at the battery. But as soon as I turn ignition ON (engine not running), voltage drops to 11.3 at the ignition switch. I worked my way back toward the battery to see where it drops off. Much to my surprise voltage is actually at 11.4 way back there at the starter. When I put negative on the battery terminal, and positive on the hot starter solenoid terminal, I'm only getting 11.4 right there. If I move the hot probe over to the battery itself I get my full 12.6 with ignition on. This seems like an awful big drop to me just going no farther than the 4 gauge 30 inch battery cable, but I guess I'm not sure what things should be. Is such a voltage drop as this normal or not? If not normal, where does this indicate that my problem is?

My first gut tells me I need to replace or at least seriously clean the connections at both ends of the hot battery cable...no time to try that tonight, but probably smart anyway. Someone tell me if I'm corrrect or if I'm chasing my tail there.

Thank you.

 

[Don S]

Re: Confunding electrical problem, 1999 Volvo 5.0GL PWTR

Disconnect the purple wires from the coil and see if that makes the change. If that doesn't do it, disconnect the purple wire from the alternator and try it.

 

[craze1cars]

Re: Confunding electrical problem, 1999 Volvo 5.0GL PWTR

Don't you hate it when you can't duplicate a problem?

Found time to play again today...I started across the battery posts for a new baseline. 12.46 volts.

So then I move the positive probe over to the red cable on the starter solenoid. Turn on ignition. It slowly starts counting down a little bit at a time, and 2 minutes later it stabilizes at about 12.2 volts. That's not bad...the other day this was taking an instant dive to 11.2-ish. But I can't duplicate that today. Grrrrr.

So, I disconnect purple from alternator. No change at all. Reconnect alternator.

I disconnect purple from coil, voltage starts coming back up, relatively quickly, to 12.45. Hook up the coil again and it gradually crawls back down to 12.2.

Is this 0.25 voltage drop normal when energizing the coil, or should I be concerned with the coil?

Of course, up at the dash I'm still only reading 11.1. Turn ignition off and up at the dash it leaps back up to 12.45. So it seems now my voltage is primarly dropping off somewhere between the motor and the dash. I'll have to start pulling things one at a time from that circuit and see if I can find the culprit. I shall choose to eat lunch first...

Please advise if a 0.25 voltage drop caused by the coil is normal or not. Thank you!