Power cuts out when ignition turned on

[ArmyChief]

This 82 K10 is trying to beat me....

Replaced the motor, now I have an electrical problem. When the key is inserted into the ignition and turned on, I have power (lights on, buzzers, etc). When the key is turned to ignition, power cuts out. No power at all. No lights, buzzers, etc. If I disconnect and reconnect the negative from the battery, I have power again, but loose it as soon as the ignition is turned to try and start the motor.

Just prior to this happening (two days ago), The motor turned over, and white smoke came from the negative terminal on the battery. Shut the motor down and disconnected the battery. Now, this....

Since this problem started, I have done the following: Replaced the alternator, replaced and secured grounding straps. Replaced all fuseable links (two by the starter and one on the firewall).

Thoughts on what I over looked? Thoughts on what is causing this?

Thanks in advance.

 

[chengny]

This 82 K10 is trying to beat me....

Replaced the motor, now I have an electrical problem. When the key is inserted into the ignition and turned on, I have power (lights on, buzzers, etc). When the key is turned to ignition, power cuts out. No power at all. No lights, buzzers, etc. If I disconnect and reconnect the negative from the battery, I have power again, but loose it as soon as the ignition is turned to try and start the motor.

Just prior to this happening (two days ago), The motor turned over, and white smoke came from the negative terminal on the battery. Shut the motor down and disconnected the battery. Now, this....

Since this problem started, I have done the following: Replaced the alternator, replaced and secured grounding straps. Replaced all fuseable links (two by the starter and one on the firewall).

Thoughts on what I over looked? Thoughts on what is causing this?

Thanks in advance.

So, just to be clear:

You are saying that the vehicle's entire electrical system is fully operational (when the ignition switch is in ACC & RUN positions). But, as soon as the key is turned to START - and an attempt is made to crank the engine - the entire system goes down. And the only way voltage can be restored is by briefly disconnecting/reconnecting the battery?

The ignition switched and exterior lighting circuits are routed separately (additionally you have replaced all the fusible links/grounding straps), so I think you can safely assume that the problem is either:

1. In the power feed between the battery positive and the "B" terminal on the solenoid, or:

2. The main grounding cable that runs from the engine (usually the alternator bracket) to the battery negative.

I don't know if you were including the negative battery cable - when you state that all grounding straps have been renewed/inspected. But, if not, I would spring for a new one - primarily based on this:


Just prior to this happening (two days ago), The motor turned over, and white smoke came from the negative terminal on the battery. Shut the motor down and disconnected the battery. Now, this....


If that doesn't help, purposely cause the issue - and before re-establishing power using the disco/reco trick - climb under and check for voltage at the solenoid's "B" terminal.

Come back - I'm interested in what you find out. This is a good one.

Oh BTW - you did check the cab to engine grounding cable - that is bolted to the rear of the RH cylinder head - right?

 

[ArmyChief]

So, just to be clear:

You are saying that the vehicle's entire electrical system is fully operational (when the ignition switch is in ACC & RUN positions). But, as soon as the key is turned to START - and an attempt is made to crank the engine - the entire system goes down. And the only way voltage can be restored is by briefly disconnecting/reconnecting the battery?

Yes! This is exactly what I am experiencing. The main grounding cable from the battery is not attached to the alternator bracket. I am running March Performance serpentine pulley kit and there is no bracket. Negative cable from battery runs to frame.

The block has four heavy gauge grounding straps to the frame (overkill, I know). Block is grounded to the cab.

The connection between the B post on the solenoid is solid.

Negative cable from battery to the frame was not replaced.

Using a volt meter, when there is power, I have 12 volts at the battery. When power is loss I have 12 volts at the battery. When power is on, I have the same at the starter. When I loose power, no registered voltage at the starter.

I don't know what the disco/reco trick is, but I will research it. I will also replace the negative cable from the battery. This is the craziest thing I have seen....

 

[HotRodPC]

Are you saying you have the negative battery cable grounded to the frame of the truck? Not the engine? If so, find something on the engine you can ground to. A head, the block, even use a bit longer bolt and go to the right front intake bolt if you have to. Even with 4 ground straps to the frame from the engine, there's alot of passing through going on. You need to get that ground directly to the engine where the starter is self grounded to the block via the starter bolts.

 

[HotRodPC]

Another idea, if you want to keep that negative cable to the frame, then get you a cable, not a strap, a cable with 2 eyes in it. Bolt one end to the bottom of the starter with the starter bolt. Hopefully it's still long enough, and it should be. Then bolt the other end to the same place with the same bolt where you have the negative cable bolted to the frame. This way you're getting a direct ground for the starter to the negative battery cable.

 

[chengny]

I don't know what the disco/reco trick is, but I will research it. I will also replace the negative cable from the battery. This is the craziest thing I have seen....

LOL - I apologize.

Disco/reco is just my lazy way of saying disconnect/reconnect - when I am sick of typing.

Anyway, about this:

Using a volt meter, when there is power, I have 12 volts at the battery. When power is loss I have 12 volts at the battery. When power is on, I have the same at the starter. When I loose power, no registered voltage at the starter.

1. If a battery is in good condition - and in a normally charged state - you will always read 12 VDC (with the probes directly on the terminal posts).

2. If you get 12 VDC at the terminal posts, move the probes to the outside of the clamps. Any reduction from the measured terminal voltage indicates a problem with the clamp to post contact. Rare but it happens. But let's assume there was no voltage drop across the clamp.

3. So, during one of these "blackouts" - and with 12 VDC verified from the battery and through the clamps - you climb under the truck. You are going to check voltage at the solenoid end of the positive cable.

4. You set your VOM to VDC. You place your meter's red probe to the "B" terminal on the solenoid. Here's a critical question: Where do you connect the meter's black probe? To the frame/body or to the engine block?

Given the fact that your battery negative is grounded to the frame - and you touch the probe to the frame - you have a bad cable. Problem is, you can't tell which one is the problem. It could be either the battery ground to the frame or the main feed cable from the battery positive to the solenoid.

Here's how to determine which cable is experiencing an intermittent loss of continuity:

Attach two long leads to the battery - one at each terminal - and bring the other ends down under the truck with you (and your meter).

1. VOM red probe to the "B" terminal & black to the frame. You read 0 VDC.

2. Red probe still on the "B". But now put the black probe to the end of the
lead attached to the battery negative. Say you then get 12 VDC...the
battery ground cable is bad.

3. If there is no change - still reads 0 VDC - put the red probe to the test
lead that runs to the battery positive and black probe to the frame. You
should then see the expected 12 VDC...the battery positive cable to the
solenoid is failing.

When a battery cable (or any other conductor) is failing, it doesn't always happen all at once. The intermittent connection has a tendency to re-establish itself, but then fail when current starts to flow. Often it can reconnect when subjected to movement (e.g. doing a disco/reco).

If one of those tests doesn't reveal a bad battery cable, come back we will keep trying.