No voltage to coil after I tried to install a Crane pointless system

[Downerman]

I'm such a dumb ass..... I have always had the worst luck with these damn things. So I replaced my plugs on my 74 Carrera. then installed this crane pointless optical unit. It didn't work as the LED never lit up so I chucked it. Put the points back in and guess what.... NADA. The frickin car is my daily driver and it was running ok, (fowled plug) hence the replacement of the plugs. I have PMO's for those who care. Anyway..... so now I check voltage at the coil and it reads .01 on the positive. If I take the wire off and check it at the wire I get 1.57 volts. I must have fried something with that DAMN crane unit. I did swap out the voltage reg and same result.

Any help would be greatly apprectiated.

Dave
(831) 521-0579

[al lkosmal]

Which ignition system are you using? If you have the Bosch or Permatune CDI system, which I believe would be typical for your 74 Carrera, you will not get 12V at the coil. Have you checked some of the basics. Did you have the distributor out of the car to install the Crane optical points? If so, is it possible that you installed it 180 degrees out? Return the engine to number one TDC and check to ensure that the distributor/rotor is correctly positioned. Did you remove the spark plug wires from the cap? If so, double check that they are in the correct positions ( I still screw this up sometimes) Are your points set correctly, and are they opening and closing. If you have a Bosch CDI, does it whine, when you turn on the ignition? Are you getting spark? Pull a plug and with it connected to a plug wire, ground the threaded portion to a good ground...engine case, etc (make sure you use something insulated when handling the plug or you will get nicely zapped) Do you get a spark when you crank the engine over. Is it trying to start or ....just nothing? Try a few of these simple checks and post the results. Others will chime in to help.

regards,

Al

[James Brown]

EDIS, quickly!!!

[jpnovak]

The Crane setup uses an infrared LED. You will not see it light up at all. however, if you have a video camera with near or zero Lux capability you can see it.

I suspect your wiring not the crane or points system.

Did you install just the optical window and trigger or the XR700 system? If the simple system you just need to put the red wire to the key-on fuse on the rear fuse panel. Ground the system and then Y splice the white wire. Send one end to the points input connection on the CDI and the other to the black/purple wire for the tach. The 12V square wave output will run your tach with no adapters.

[Downerman]

Hey thanks guys... more info. I didn't pull the Distributor out of the car, in fact all I did was change all the plugs, new cap and rotor then tried to put the XR700 in the distributor and hook it up. When I was done, or at least thought I was done following their 9000 different types of setups in the instruction manual the engine would just turn over and NADA. I spoke with their tech guy and he asked if the red LED on the control box was lit, not the optical reader... when it was cranked or with the key in the on position. There was not. Sooooo I pulled the crane stuff out, put my points back in and now.... it cranks but nada. Not even a misfire.

So... .I should'nt have 12V at the coil? I was told by the crane guy who is NOT a porsche guy that I should have 12 V at the + with the key on and then tap the negitive and the voltage should drop to around 8 because of the ballist??? might have that name wrong but it's the gizmo that reduces the voltage for the points.

Electircal is my worst nightmare....

Dave

[al lkosmal]

Downerman,
With the Crane installed, you may have 12V at the coil, but you said that you removed the Crane stuff. My 1st question was, and still is, what ignition system do you have in there now? My comments regarding not getting 12V at the coil, were based on either the Bosch or Permatune CDI (capacitive discharge) units. These would be the typical, standard ignition systems you would probably find in your 74 Carrera. You mentioned that you took the Crane out.... and went back to points. It's not clear what ignition system do you have installed now? Take a picture of the system and the wiring and post it. It will help with the debugging efforts, communication, etc.

regards,

al

Regards,

Al

[E Sully]

When checking the coil for voltage the negetive lead should be grounded to the chassis ground and the positive lead should go to the + of the coil. You will not get a proper reading across the coil +, - leads.

[Downerman]

Al, it's all stock now. My daughter ripped my camera off to take to college so I'm trying to borrow one. But it's all stock 74 electrical. The original engine is out and sitting in my garage and the replacement is a 72 2.4 S engine that has been rebuilt. Bosh Dist. All I have is a white wire comming out of the harness that goes to the points and of course the wires that connect to the coil. The car has been running great for a couple years... everyday!! (less the fowl'd plug issue mentioned above)


I'm checking voltage from the + of the coil and the black lead of my voltage detector is grounding to the car NOT the - of the coil. My mechanic who hates electrical as well says he thinks it's a CD unit. I need to confirm this.... anyone know how to?

Dave

[Walter_Middie]

There are three wires going to the original CDI unit, two white wires and a red one. Of the two white wires, one goes to the + coil (or transformer) terminal, and the other white wire goes to the distributor points and the tach. The red wire is +12 volts switched through the ignition switch on the dashboard. Each of the white wires is wrapped with a grounded shield that is connected to the CDI unit case at one end, and the + coil white wire ground shield runs to the – coil terminal and is grounded on one of the posts that the coil mounts on, the other white wire ground shield is grounded on the engine near the distributor.

I don't think you can test for voltage at the coil, as it is some ridiculous amount like 450 volts.