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Low voltage to hall effect and coil

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Old Dec 19, 2008 | 04:36 PM
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Default Low voltage to hall effect and coil

I have a 1988 Ram w150 318 w/tbi. It was was running fine then started to sputter then died and won't restart. It tries to start but sounds like it's only firing on 2 cylinders. I replaced the hall effect and coil with no results. I checked the voltage to the hall effect and coil and they're only getting 9.5 volts. Spark is yellow. After this I replaced the body ground with still no luck. Engine has good ground. Computer is not original, was replaced sometime before I bought the truck. Any help would be appericated. Thanks.
 
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Old Dec 19, 2008 | 07:41 PM
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ballast resistor?
 
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Old Dec 19, 2008 | 07:55 PM
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No ballast on an '88. Everything gets it's juice through the ASD relay,the computer grounds the neg. side of the coil when it receives a signal [change in resistance] from the hall effect. Check upstream and downstream of the ASD,see if there's 12v to/from the relay. Let me check my FSM. Think there's only supposed to be 5v to the hall effect best as I remember.
 

Last edited by lugnuts; Dec 19, 2008 at 08:01 PM.
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Old Dec 19, 2008 | 08:40 PM
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According to the Haynes manual and a mechanic at the local Dodge dealer, the hall effect is supposed to be within 1 volt of the battery to opperate correctly. As far as I know their is no crank sensor on my truck, so I'm unsure if it even has an asd relay because it has tbi instead of mpfi which has a camshaft position sensor that uses a 5 volt signal. The book says nothing about the asd relay. If you could tell me where it's located, I'll check it. Thanks for the help.
 
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Old Dec 19, 2008 | 09:01 PM
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All I can find is my '89 book. Let's back up a minute. Is the battery at 12v or 9.5? Should be 5v supply to the hall effect. The 5v supply also feeds the map,tps etc, see if you have the same voltage on the blk/lt blue wire at the tps.
 
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Old Dec 19, 2008 | 09:05 PM
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Wanting to verify the 5v circuit isn't shorted.
 
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Old Dec 19, 2008 | 09:23 PM
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Battery is showing 12.4 volts. As I said in my last post, a Dodge mechanic and the Haynes manual both say the hall effect runs within 1 volt of the battery voltage on TBI systems. The ignition coil is also only showing 9.5 volts, like the hall effect. If it had a camshaft position sensor, like the MPFI equipped models have, it would be 5 volts. The computer is showing 12 volts at the power input. Could it be the computer is bad? The original hall effect was shorted out by the previous owner leaving a piece of metal in the distributor housing, which i found when I pulled the cap. TPS checked out for 5 volts, I thought the same at first. Thanks.
 
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Old Dec 19, 2008 | 09:39 PM
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I look at it this way, if all else fails it's time to pull out the electronics and drop in a point distributor and a 2 barrel Carter.... lol
 
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Old Dec 19, 2008 | 09:42 PM
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Wiring diagram shows a 5v reference. Tell you what, just so happens I have an '88 318system on my '86 Ramcharger. Let me do some comparing voltages to yours tommorow,see what mine has where. Fair enough?
 
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Old Dec 19, 2008 | 10:00 PM
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Thanks lugnuts, I really appreciate all the help. Just got this thing 3 weeks ago and have come to the conclusion I inherited someone elses headache. Rear axle still needs to be rebuilt from someone beating the old yoke off with a hammer and blowing the input bearing and seal, then driving it with no fluid. Gotta get this thing fixed. Gotta plow the driveway somehow and the snowblower ain't happy with me lately either... lol
 
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