Testing continuity

[98SZR]

Hey all,

Some stage this weekend between helping with my mates 1uzfe and watching Geelong win the grand final I thought I might do some electrical testing on my 2jzgte in the supra.

I have had a small electrical gremlin that pops up every now and then which I believe is one of my bad solders in the fuse box for the efi2 relay. The symptoms are when I've driven it for a while occasionally (very randomly) it will cut slightly (like boost/fuel cut feeling) when just cruising along. The only custom wiring I have done is EFI2 relay setup (as car was originally NA I changed to TT wiring layout) and also extended the o2 sensor wiring.

I really just want to confirm that to do a continuity test to check the wiring is to disconnect the negative terminal and test all efi related fuses and connectors/pins. I haven't done much in the electrical department for a while and really just wanted some guidance.

Cheers

[o_man_ra23]

To do a proper point to point check, remove plugs at both ends of the connection. The wire being tested should not be connected to anything at either end. To test, go to one end and check the resistance to earth, it should be open loop. Then ground one end and check resistance to ground at the other end. It should be max 1-2 ohms (cheaper multimeters have inherant resistances, and so do connections). Ideally it should be a few milliohms. When testing, test after the solder/join... so that your test current is going through the join. You dont need to disconnect the battery. If you are suspect on the joins, and no test comes up positive, re-solder and hope for the best. I sincerely hope you didnt mess with the wires on the oxy sensor, and just did the loom wires going to it.

Hope this helps.

[98SZR]

To do a proper point to point check, remove plugs at both ends of the connection. The wire being tested should not be connected to anything at either end. To test, go to one end and check the resistance to earth, it should be open loop. Then ground one end and check resistance to ground at the other end. It should be max 1-2 ohms (cheaper multimeters have inherant resistances, and so do connections). Ideally it should be a few milliohms. When testing, test after the solder/join... so that your test current is going through the join. You dont need to disconnect the battery. If you are suspect on the joins, and no test comes up positive, re-solder and hope for the best. I sincerely hope you didnt mess with the wires on the oxy sensor, and just did the loom wires going to it.

Hope this helps.

Thanks Mate, great info.
No didn't mess with the wires on the oxy sensor, just removed aristo jzs161 plug end, extended the wires and added supra loom plug.

[brett_celicacoupe]

checked for error codes?

maybe get a panel and mount 10 LEDs in it and moniter every critical pin for the engine to run. moniter +B, INJ supply, IGN, BATT etc.

theres about 6 that are required for the engine to run.

drive around, wait for the problem to occur again and then you can see if any of the vital circuits have faults

[98SZR]

I really should check for error codes! I have the obd-II engine diagnostic codes just have to confirm the correct terminals for the vvti for checking error codes as I can't remember where I seen them.

Also one thing that crossed my mind could be something really simple, I remember one of my coilpack clips is broken, it may heat up and maybe move around a bit potentially causing issues/cutting out like it is, will check that too! Once I rule that out and have doen a few tests on the electrical system I might try your testing method Brett.

[o_man_ra23]

Hmm... loose coilpack clips might not be a great help... best you should have fixed that when you discovered it

Lesson to all, fix things before they become problems!!

[98SZR]

Yes I should fixed it but thought it was in tight enough, but never thought of when it heats up! Little mistake on my behalf.

I have a crappy diagram here of how the EFI stuff is setup, most of the soldering is from 2 and 5 on the efi relays to the engine (plugs under the fuse box), so to test that I would remove both fuses and engine plug (as seen in picture) and test each end, (IE: One probe on engine plug pin, one to earth, then for the other end go from one of the relay pins in fuse box to earth?)

[o_man_ra23]

I would pull out both relays and not bother with the fuses. with the relays out, and engine plug apart, there should be no circuit. If the wire is joined in the middle and goes to several points (looks like yours has 4 points of connection) test every point of connection individually, with one earthing point. If all of them show signs of being stuffed, its your earthing point that is buggered. If only one shows signs of being stuffed, its the tested point. If it looks like the earthing point is stuffed, but it cant be fixed, its where the points all connect thats bad.

Have you thought about buying the proper slip in crimp ends?? You can usually buy them in a strip of 10 from Jaycar/Sniff Dick in a variety of sizes. If they are a fairly standard type of pin, then for the $1 or so you spend buying them, they are much better than a dodgy solder join.

[98SZR]

I would pull out both relays and not bother with the fuses. with the relays out, and engine plug apart, there should be no circuit. If the wire is joined in the middle and goes to several points (looks like yours has 4 points of connection) test every point of connection individually, with one earthing point. If all of them show signs of being stuffed, its your earthing point that is buggered. If only one shows signs of being stuffed, its the tested point. If it looks like the earthing point is stuffed, but it cant be fixed, its where the points all connect thats bad.

Have you thought about buying the proper slip in crimp ends?? You can usually buy them in a strip of 10 from Jaycar/Sniff Dick in a variety of sizes. If they are a fairly standard type of pin, then for the $1 or so you spend buying them, they are much better than a dodgy solder join.

Yes that's what I was thinking, just trying to get my electronic skills back up to scratch. The only thing I was really worried about was if to disconnect the battery or not, but if the relay and engine plug are out then there is no way for it to get power, as long as both ends are undone

At the time I didn't think of using crimp ends or anything with the word crimp in it! lol! I hate crimping! But I'm sure if there is any problems with my solder I might crimp and apply a tiny amount of solder. I don't mind using the twist, solder, heat shrink method.

[o_man_ra23]

I don't mind using the twist, solder, heat shrink method.

Reminder to self, dont get 98SZR to do any wiring on my car

[98SZR]

Reminder to self, dont get 98SZR to do any wiring on my car

lol!

Ok so lucky for me I had a spare coilpack plastic connector/clip on my old aristo jzs161 loom so I could use that, of course the broken clip was the one right up the back, so that's now out of the equation.

As for the electrical testing (proper diagram below) all open loops were tested which is:

EFI Main relay pin 2: 10ohm (I suspect this one at potential fault)
EFI Main relay pin 1: 0 - Perfect
EFI No.2 relay pin 1: 0 - Perfect

All the others are closed loop so won't give readings unless I had of removed fuses/ B+ for fuel pump ecu

So I believe EFI Main relay pin 2 is at fault (maybe) as it was the only one not to show 0. This is an earth as you can see on the diagram, which could explain why the car can have this cut issue, no earth on a main EFI and no.2 relay would most likely cause the car to cut! No fuel etc etc Wouldn't you agree? Will test car over next few weeks (only drive it weekends) and see if it happens, if it does then I will re-solder it and test again.

[IMG][/IMG]

[cambelt]

One thing i had was a faulty fuel pump ecu , mainly when idling it would cut out start again then stop . Yr not running some big current draw fuel pump ar you.
Also depending on the country i think EFI 2 is wired different some efi 2 run injectors as well ( maybe U S)
Dave

[98SZR]

One thing i had was a faulty fuel pump ecu , mainly when idling it would cut out start again then stop . Yr not running some big current draw fuel pump ar you.
Also depending on the country i think EFI 2 is wired different some efi 2 run injectors as well ( maybe U S)
Dave

Yes will do more testing of fuel pump ecu wires to the relay if the problem persists, the problem's only happening on a long drive once it gets hot, bumps/too much acceleration make it cut. No running stock pump, but did the efi2 upgrade so when I go bosch 044 and single turbo It's not running through 1 relay like the NA setup.

As far as the US stuff goes lucky for me I checked the jdm 2jz vvti diagram I had and it's exactly the same as the US one above, pretty much most of the US wiring is the same with the exception of trac/abs and a few other things

[o_man_ra23]

I think you may have found your culprit. Check every join that that connection goes through that no other connection does (even on the same circuit). Sounds like it might just be that simple. Heres hoping.

[98SZR]

Yes just went out and tested anything that is connected to it, kept efi2 relay in and tested the dodgy efi main pin 2, then swapped and left the main relay in and tested anything that is in circuit with the dodgy one, seems it is the one I first thought.

All the other connections are fine and give 0hms. The only one that is faulty by the looks of it is EFI Main relay pin 2 with a reading of 10ohms, then when testing efi2 with efi main relay in, the efi2 pin 2 gave a reading of around 3ohms (which is connected to the faulty efi main pin 2 as they are both earths). So I have came to the conclusion that EFI Main relay pin 2 is at fault (earth).

Another test I used was Using the faulty earth as the earth when testing other pins and it gave 10hms so it has to be that one, also tested with the engine plug in and same results, will check over it and resolder tomorrow as it's beer o clock. Thanks for all the help guys, will let you know how it goes tomorrow.