[cevebed]

Hello guys any help or advice is greatly appreciated.

1997 f350 7.3l 5sp

During a normal startup process the truck would starts up and for a short period of time there will be lower voltage then it will kick up to the higher voltage.

What is happening to me is the truck starts up fine with no issues then instead of what i mentioned above the voltage will bounce between the lower voltage and the higher voltage for about the same duration of time then it will stop and stay at the higher voltage.

After this process the truck runs fine now issues no codes. anyone have any ideas?

thanks again

 

[bugman]

The lower voltages you are seeing is because of the glow plugs. They draw a huge amount of amperage, around 190 amps when they are first activated and they will stay on for up to 2 minutes after starting.

The pulsating you are seeing may be the relay kicking on and off. It could be the relay or the ground that the PCM sends to activate the relay.

 

[cevebed]

The lower voltages you are seeing is because of the glow plugs. They draw a huge amount of amperage, around 190 amps when they are first activated and they will stay on for up to 2 minutes after starting.

The pulsating you are seeing may be the relay kicking on and off. It could be the relay or the ground that the PCM sends to activate the relay.

mmmm i ill have to check and clean my grounds to start with because i remember once this last winter i was leaving my house and i had saw the voltage completely drop to zero. i had pull off the road and let is idle for a second then open the hold and all of a sudden i had normal voltage again. Besides the pulsing i have experienced before and after this event took place.

 

[Steve83]

Get a digital multimeter and post the actual numbers. This is a decent one for automotive hobby use at a reasonable price:



These pics show the things that you should concentrate on:

. .

Inspect the drivebelt for slipping, and the pulleys for glazing &/or contamination.

 

[bugman]

I don't believe that it is a charging issue since everything is fine once the relay quits cycling.

I had a relay do it one time on me but that was it and I never did try to trouble shoot it out.

When I said the ground I meant the ground that that PCM supplies to activate the relay. It comes from the PCM and not the battery.

You might also want to check the connections on the relay or even change it out as a maintenance item.

 

[Steve83]

The load of the GPs can momentarily aggravate an otherwise-latent charging system fault, like a slipping belt or poor connection. But even if your truck has NO electrical problems, it's worth checking all those things as maintenance items.

 

[bugman]

I also think that he should check the rear end fluid also.

But that has nothing to do with the problem at hand.

 

[cevebed]

I had a relay do it one time on me but that was it and I never did try to trouble shoot it out.

its a good chance it could be the relay. im going to dig into it this week but i do appreciate the help so far. ill report back when i ahve more info.

-cev