Where do I splice the line for the inline 1 amp fuse for the Aux pump here in the photo? The two lines to the left going into motor or the line to the right where I assume is the switch?? 77 300D with the "evil servo"

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Need to check the amp draw while it's working first to determine normal draw because it is going to be more than 1 amp. It should be the one next to the pump housing.

The fuse should go in the supply to the pump. Remove the connector and check which is hot. One wire is usually Brown which is ground .

Use a fuse with a rating a couple of amps above normal draw.

In the pic it would be the the line on the left???? Does anyone know what the amp draw is for the pump and what size fuse to use??

Use a 1A fuse.

When I checked the draw on my '83, it was .65 amps. The one amp fuse works fine.

If I am not mistaken, I don't think "evil servo" cars need a fuse in the line.



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1983 123.133 California
- GreaseCar Veg System

Would that be because they don't use a computer circuit board ? Thought I'd ask.

...and as for a motor using less than 1 amp...did you arrive at that measurement with a digital amp clamp? Seems really low.

In 2006, I measured the current draw of my '85 300D aux coolant pump as 0.9A at 12.6V using a Goldstar DM-311 DVM (in-line, not inductive) so I fused the pump at 1.5A. Electric motors tend to draw a bit more current during start-up and I found that a 1A fuse would sometimes blow after a few uses. Others have had no problem with a 1A fuse so I suppose there are slight difference from motor to motor.

Jeremy

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"Buster" in the '95

Our all-Diesel family
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In not needing a fuse for the cars with the "evil servo" how do you protect the amplifier from getting fried if the pump keeps working??

Dunno, do I? How do you?

I did a search on the board going back a few years and yes you do need to fuse the aux pump even with the cars with the "evil servo" in it.

Here is what JimmyL posted a few years back. So I answered my own question. Love the search options on this forum!!!!

"That servo amp is very likely your problem. I've never pulled one out of a car at the yards that wasn't fried. Most of them you can see the burned area!!"
"I hope your mechanic fused your aux water pump. If not you need to do that or have it done."

Well done that man. Thanx for the info'.