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EZK - Coil - Spark Issue

15A

World's Oldest Brewery
Joined
May 7, 2004
Location
OH-MI....just like it sounds
Wondering if anyone here knows how the coil gets 12V - is it switched from the EZK? Or straight from the ignition switch? The schematics leave alot of possibilities and I have found many connectors that are never shown.

I have a no start issue with no voltage at the coil on a 93 setup (without the PAL fuses). Have checked wiring continuity from the power stage to the coil to the EZK to the fuse panel. All check out. 12V at the EZK is also present. Everything is new (which means little in this day and age) - but no Uro garbage or the like. Power stage is new (I swapped another out anyways and thats not the issue) - CPS is a new Bougicord. My only thought at this point is its not getting 12V from something thats not getting a signal from something else - but still always believed if the key was on, it would have 12V.

I have never seen a bad EZK but sure its possible. Before I go pulling the CPS I'm wondering if I could put an ohm meter on it and check it while cranking. 99.999999% sure the flywheel is orientated correctly (was test run before installed). The one area I have yet to check is the (new) ignition switch. Its a bluebox special (which also means nothing) but felt very rough to turn - was nothing smooth about it. I have a low mileage used one thats probably better. Will do some continuity tests between it and the coil wire as well. I have also heard of people jumpering 12V to the coil. Doesn't sound good.

I have seen this issue on older posts elsewhere and no one ever follows up with wtf they did (bought a Honduh?).

Any useful thoughts or BTDT's?
 
1993-240 (EZ-116 K) - Ignition switch feeds directly to coil, pin 6 on EZ, and pin 4 on power module. LH has nothing to do with coil
 
There should be 2 blue wires on coil +12v. One comes from a body harnesses by the driver's fender and supplies +12 from the ignition switch. The 2nd wire goes to the ignition module, using part of the engine harness.

Elsewhere in the engine harness, there is +12 to the EZK, but for whatever reason, Volvo chose to route the coil +12v wire separately. (Maybe due to radio noise? -- some of the later 740/940s have a RSR radio suppression relay that supplies coil +12v.)

Quickie edit: there are 2 pin 15's on the ignition switches. Some years, they do the same thing. Other years, one of the pins drops power during cranking (shuts off un-needed accessories to give better cold weather cranking). This causes problems when the wrong pin/switch is used and coil/injector power goes away during cranking.
 
Elsewhere in the engine harness....

If California spec'ed 1993 240, ignition wire to coil fed several other circuits....needless to say, if any of those wires were grounding out somewhere a pinch...limited current.
 
Quickie edit: there are 2 pin 15's on the ignition switches. Some years, they do the same thing. Other years, one of the pins drops power during cranking (shuts off un-needed accessories to give better cold weather cranking). This causes problems when the wrong pin/switch is used and coil/injector power goes away during cranking.

Im going with this one. I have one of those switches in my 77 that came from a 91 donor car. I read about that problem in the "How to convert to LH2.4" thread and was able to confirm i had one of those switches with a multimeter. I set it to the continuity test mode and sure enough when the key is turned all the way to start the circuit goes open.
 
What the green manual never mentions is the difference between a 93 harness and everything else. 92 and before had 2 wires crimped in a single blade connector on the coil. With the same drawing in the 93 book, they actually had 2 different pairs of single wires connected to the coil.

How I found this was I had zero continuity from the first pair and the ignition switch or the tach. I had seen a second pair of identical color coded wires (with damaged ends) tucked into the main harness down stream.

Behold:

P1030755x.jpg


That second pair was the 12V and tach......the first pair comes from (or goes to) the power stage.

Once I got this all figured I now have a battery light that is off when running but on with the key off and out. Beautiful things these cars are.
 
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