Reimu

That strip connects to a lot of things and directly to pins 5 (reference sensor shield), 6 (air flow sensor), 23 (speed sensor shield), and 19, which is the ground.
It seems as though it tried grounding too much current through pin 19 and zapped it there, at least that's my best guess.

In a fit of mild rage I pulled the entire engine harness and tested each individual wire to see if it was making contact with any others. The only wires that were in contact with one another were 16, 17, and 19, all grounds so I assume the engine harness is fine. I don't see any broken places for wires to be contacting the engine itself.

Yesterday when I was stranded when I first put the key to accessory the oil pressure gauge pegged itself. It would flop up and down as I turned over the engine.

I've tested the power to the DME before and was getting proper voltage.

thomasmryan

...demonic possession in the battery cables or the voltage regulator..if the oil gauge it pegging like that the voltage potential at the motor must be pretty low. A VOM is going to read potential unless you stick it in the dirt outside.

I would check....Battery to chassis cable ....chassis to bellhousing....starter bundle(or starter itself)....ignition switch....internal alternator short.

Reimu

Whole alternator is new, same issue happened with my old one/voltage regulator.

I've checked all the power cables and they're perfectly fine. I did notice that the post on the starter that the battery cable connects to seems to ohm out on the starter case/bellhousing. Should it be doing this?

thomasmryan

I can climb under and check the internal resistence in the morning...searching revealed nada. Assuming a 100 amps at 12 volts, the internal resistence of the starter is going to be around 0.1 but it should be isolated unless the bendix/solenoid or starting circuit is janky.

thomasmryan

The meter fluctuated between 0.3 and 0.4 ohms. The PET says 1.7kilowatts so I have some internal resistance in my meter and at the brushes. Should be around 0.1.

1700watts/12volts is about 142 amps. If the internal resistance is .1..... 142 amps x 0.1 would be 14 volts. Within the ballpark anyway.

Reimu

Well that's odd. I'm getting 330ohms from the positive terminal on the starter to the starter case and bellhousing. I've checked, rechecked, and rerechecked the main wires and none of them are touching anything or out of place. Tried putting in a spare starter and got the same results.

marc abrams

Reimu, checking ohm's like that means nothing. To many parasitic loads in the car even when the car is off to be useful. The short may be in a component like AFM or a heated O2 sensor (if equipped) . The first thing I would check is body to engine ground by doing a voltage drop test. This video will give you a idea how to do it,

Reimu

Negative battery terminal to engine gets me 0 drop at everything except when I turn over the engine, which pulls .4 volts
Battery to starter gets me 0 drop with key off or on accessory
When turning over the engine it gets up to a little over half a volt
No trouble turning the starter

Tiger03447

Dear Reimu you should only be getting very low parasitic draw from the battery..which in a lot of cases is just the DME which stays on all the time...You should get a drop when you open a door or turn something on..this is normal..
Do you have a glass hydrometer? Perhaps Harbour freight has them still. When you charge up a battery, check the amount of charge with a hydrometer, even if a meter tells you it has 12 volts.. In glass hydrometers, the amount of charge is reflected in the colors on the float which is inside..Green is excellent, White is OK and red is flat...When the amount of charge is at it's max, the level of the float will be in the green. You can put up to 13.2 volts into a battery...that is it's maximum level of charge that is OK for a 12 volt battery...If it has more than this..it is overcharged and that is not a good thing. Each cell can put out 2.2 volts..X 6 # of cells..=13.2 Volts...An alternator should put out between 13.5 to 15.5 volts with all accessories off...if you are getting 14. 2 output from the alternator, you are doing great...When you go to AutoZone, be sure to get the test results printed off..then you have a record..the # of volts output should be on the yellow tape....thanks, Tiger 03447

marc abrams

Does your negative battery cable goes right to the engine or to the body or both?

Reimu

Engine and firewall

I checked the voltage drop on the ignition switch and ignition coil and those hardly registered anything. I don't get it, diagnostically everything is fine.

Think it's possible that this last DME burn was a fluke, like the solder fell off of the circuit and grounded spark started arcing on the board until it broke off completely?

Tiger03447

Dear Reimu sounds like it's time for the ECU doctor...

marc abrams

Reimu, can you do a voltage drop test between the battery and the body turning everything on in the car. Also how many wires are on your O2 sensor? Solder falling off the board? I've never saw anything like that, but hey anything is possible!

Reimu

Positive terminal to engine
Off: 12.60
Engine running: 14.08

Negative terminal to engine
Off: 0
Engine running: .06

I'm starting to fear this might have been some intermittent issue
Car runs nicely though

Tiger03447

Dear Reimu: The 12.60 is battery voltage...the 14.6 reflects the extra juice coming from the alternator..BTW. speaking of alternators, wiring and such..when you go to work on a car, be certain to undo just the negative cable..reattaching it poses no problem. Disconnecting a positive cable with the negative still attached poses no problem..but when you REATTACH the Positive cable while the negative is still attached CAN cause problems as it surges the diodes in the alternator and MAY cause the to fail...this is due to the voltage spike the alternator diodes receive when the cable is re-attached.....