On 9/7/09 DIY.com member "sand8570" referred to "...a small detent spring..." that appears to press against the side of the filter cap. In another member's photo of the cap the detent spring looks like it might act like a pawl, and would have to be lifted out of each detent in the cap to allow the cap to be turned counterclockwise for removal. Is that the case?

I was working at this rental today and this old guy was interested in buying the tenants 4 x 8 trailer. He got me involved, when he found out I was 'handy', because he did not know if his pickup truck's jack connector was the right one for the trailer jack. Plus he said he cannot hardly see. It was. It was in sorry shape with crud in some of the female terminals and green corrosion. I cleaned it all up for the guy. Then I volt meter tested. I was only able to get 12 volts from one jack terminal to the green wire jack terminal, no matter what we did in the way of............ ...well.......this is the mystery: The jack has 4 total terminals of which 3 are female, and one is male. One of the female's is the green and carries the ground. So answer me this: How can the trailer have 1. Lights on - 2. stop lights - 3. Left directional, - and 4. Right directional....when there are only 3 terminals and a green ground wire terminal? ??????? The old man tired of my testing and questioning finally said, "Let's just pull up to the trailer, hook my jack to the trailer, and see what happens." Well, right off the bat, the lights were on, but really dim. You could only see the faint glow when looking into their lenses head on. Then he tried one of the directional signals and they worked, but were dim. The brake lights did not cause the lights to get brighter, even though they did on the pickup itself. The pickup's jack connector, and about 18 inches of that flat wire containing the 4 wires, was spliced into the individual wires near the rear of the truck. And one would presume that whoever did it (the old man bought the junk pickup truck that way) got it right, or else would have redone the job till it was right. But for some reason, I had either no power or like 4 volts of power to say a couple of those terminals. (Yes, I had thre polarity correct for DC testing, but I even switched my probes just to make sure) If it was MY truck, I would have guessed the connectors got corroded inside and needed to be redone, even though by looking at these specail square plastic coated connectors, I saw no evidence of salt/ corrosion The old man said he'd take care of it. But what is still vexxing to me, as I am not familiar with trailer wiring jacks....... even if 3 of the terminals of the jack had 12 volts for each proper light function, along with the 4th ground terminal.......how on earth do you get the [U][B]4[/U][/B] functions that I listed with only [U][B]3[/U][/B] wires + ground? Yet, that was a typical standard jack. You always need lights at night + brakes + left signal + right signal. ?????