My car has been running poorly for ages..... and also, constantly drains the battery, despite having minimal current draw. I just tested my grounds and there appears to be a ground loop. From the negative terminal to where the battery cable connects to the chassis, I'm reading about 15 ohms (brand new battery cable). Touching the alternator body to the main engine ground (which i've replaced with a ground strap) i get a hign ohm reading also.

Also, alot of noise in the stereo which is now disconnected to eliminate it as being part of the problem.

Where should i start to diagnose my bad ground? I've fortified all my grounds and still have the problem.

Thanks,

Matt

 

As a quick guess, I'd say that you may have an alternator or possibly a voltage regulator problem.

Have you checked the charging voltage while the car is running (as measured across the battery) with out any electical item on? This should be at least 14v otherwise there won't be enough voltage to keep the battery charged.

The voltage regulator should also respond to increased current demands by increasing the alternator output to match the increased load, if it does not it should be replaced.

 

Please define main engine ground. Normal grounding is from the negative battery terminal to the chassis below the left strut tower...then from that spot to the long bolt that attaches the starter. It sounds like yoou have a different arrangement.

High readings would indicate the attach points to the chassis and or the engine(long bolt on the starter), are not secure/clean from paint, oil, grease, rust etc.

I get .1ohm from the alternator body to the negative post on my 87 and it has stock from the factory grounding. Original cables.

 

The alternator is operating fine..... in fact, i have upgraded to an FD3S alternator and am getting a steady 14+ volts.

My grounding arrangement is "stock". The main engine ground i was referring to (probably incorrect terminology) goes from the back of the engine block to the firewall which i beefed up with a grounding strap. I replaced the ground from the battery cable to the strut tower, however did not do anything from that point to the starter.... perhaps that link to the starter bolt is what is suspect?

Thanks,

Matt

 

Without a doubt.

 

I checked the cable going from the strut tower to the starter bolt, and it appears to be in good shape. With the cable disconnected, i do not measure any resistance across the wire.

Moving along, when the key is off, there is no resistance (less than an ohm) in the system. As soon as i put the key in the on position is where im getting the 5+ ohms just from the neg battery terminal to the opposite end of the ground strap i put from the terminal to the body.

Where should i look next?

Thanks,

Matt

 

anyone have any suggestions?

Thanks

 

check resistance on a non-energized circuit.

if circuit is energized, check the voltage.

you don't check resistance on an energized circuit, at least, that's what I was always told.

Hugues -

 

im intertested in this also....i dont know if i have a cable going from my driver's side strut tower to the long bolt on the starter. Is that bolt on the up or down side of the starter?

 

if you have doubts on the wiring for the charging system,
look at this thread on how to rewire it hypntyz7 style:

https://www.rx7club.com/showthread.p...hreadid=143914

Hugues -

 

****you don't check resistance on an energized circuit**

DITTOS.