3.0 GL

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ChristoSlang
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Full Name: Christo van Rensburg
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Current 4x4: Nissan 4.2 GL Patrol
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Re: 3.0 GL

Post by ChristoSlang »

The oil pressure warning light on the dashboard works from a switch type sender unit. It only has two positions - on or off. Think of it as an on/off light switch. The Madman on the other hand can use a variety of pressure senders, but all of these pressure senders have a variable signal in response to variations in oil pressure. Think of it as a dimmer.

The VDO type sender in my Patrol is a resistive type sender, and as the name says their resistance varies according to the oil pressure. These sender units are VERY sensitive to bad connections (the wire going to the sender itself) or bad earthing (where the sendr screws into the block, or the Madman's earth). They will typically show very high readings or wild fluctuations when this is the case. If it used to work properly, it may simply be dirty. Pull the lug off the sender, clean it well (carb cleaner, etc.), maybe give it a light crimp again and fit it tightly back onto the sender. If you're lucky (like I was), this is all that's required.

If not, you'll need to follow that same wire for joints that have gone bad with age, etc. Also check the Madman's earth position and condition. Here are two important quotes from the installation docs:
  • "Apply Loctite thread sealer to pressure and temperature fittings – thread tape may cause electrical connectivity problems."
  • "When doing the wiring for the unit it is critical that you fit the black earth wire to the engine block – failure to do so will possibly result in erratic readings as other loads are switched on such as lights, fans, indicators etc."
PS: The newer Madman supports voltage based senders - these are much less sensitive to bad connections...
Christo (the snake man)
1998 4.2 GL Patrol (Chuck Norris)
2007 350Z twin-turbo coupe (Batmobile)
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Rodney
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Re: 3.0 GL

Post by Rodney »

Thats Christo. Thats useful info.
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