Battery Issue - One for the Auto Electical Gurus
Discussion
I'm hoping you can help.
I recently bought an Optima Red Top battery (RTU 3.7) from a retailer in the UK (Battery Megastore) and I've had no experience with these batteries before, but plenty of experience with auto electronics. I'm experiencing an electrical issue in a race car that I'm building that uses a Mazda MX5 chassis and uses a negative ground. I'm having some strange problems where the car won't start and when I've checked the 12V supply from the battery with everything detached except one ground strap from the battery to the chassis, I'm getting a continuity to ground through the 12V positive circuit. This is not something I've experienced before with standard batteries and after testing this with the original battery, this does not happen. I was wondering whether there is an issue with the battery or this is normal behaviour for this battery - Or any suggestions you may suggest?
TIA
I recently bought an Optima Red Top battery (RTU 3.7) from a retailer in the UK (Battery Megastore) and I've had no experience with these batteries before, but plenty of experience with auto electronics. I'm experiencing an electrical issue in a race car that I'm building that uses a Mazda MX5 chassis and uses a negative ground. I'm having some strange problems where the car won't start and when I've checked the 12V supply from the battery with everything detached except one ground strap from the battery to the chassis, I'm getting a continuity to ground through the 12V positive circuit. This is not something I've experienced before with standard batteries and after testing this with the original battery, this does not happen. I was wondering whether there is an issue with the battery or this is normal behaviour for this battery - Or any suggestions you may suggest?
TIA
Not understanding what you are saying.
You're testing the wiring between 12v and ground "with everything detached"
so no battery in place ?
Yet you are questioning the battery ?
And when you say it wont start, exactly what do you mean ? no power, it wont turn over, nothing, it goes on fire ? Specifics.
You're testing the wiring between 12v and ground "with everything detached"
so no battery in place ?
Yet you are questioning the battery ?
And when you say it wont start, exactly what do you mean ? no power, it wont turn over, nothing, it goes on fire ? Specifics.
Thanks for the reply.
Everything detached apart from the battery and one earth strap. Even with the earth strap disconnected, I am getting continuity between both terminals of the battery. My question is, from all my years doing auto electrical stuff, I have never seen continuity between both terminals or from 12V to ground - do you think this is normal or would this high resistance point towards a duff battery?
The battery cranks the engine over very well. Overall I have an ECU issue not firing injectors or coils, and all checks I have performed come back OK... crank and cam sensors, grounds etc. So when I noticed that most sensors have a 12V supply that ALSO shows continuity to ground on the same wire, it makes me beleive that the issue lies around there.
Any thoughts please?
Everything detached apart from the battery and one earth strap. Even with the earth strap disconnected, I am getting continuity between both terminals of the battery. My question is, from all my years doing auto electrical stuff, I have never seen continuity between both terminals or from 12V to ground - do you think this is normal or would this high resistance point towards a duff battery?
The battery cranks the engine over very well. Overall I have an ECU issue not firing injectors or coils, and all checks I have performed come back OK... crank and cam sensors, grounds etc. So when I noticed that most sensors have a 12V supply that ALSO shows continuity to ground on the same wire, it makes me beleive that the issue lies around there.
Any thoughts please?
ChrisPackit said:
Thanks for the reply.
Everything detached apart from the battery and one earth strap. Even with the earth strap disconnected, I am getting continuity between both terminals of the battery. My question is, from all my years doing auto electrical stuff, I have never seen continuity between both terminals or from 12V to ground - do you think this is normal or would this high resistance point towards a duff battery?
The battery cranks the engine over very well. Overall I have an ECU issue not firing injectors or coils, and all checks I have performed come back OK... crank and cam sensors, grounds etc. So when I noticed that most sensors have a 12V supply that ALSO shows continuity to ground on the same wire, it makes me beleive that the issue lies around there.
Any thoughts please?
Cant say Ive ever deliberately put a meter across a battery when on ohms. So really cannot comment there.Everything detached apart from the battery and one earth strap. Even with the earth strap disconnected, I am getting continuity between both terminals of the battery. My question is, from all my years doing auto electrical stuff, I have never seen continuity between both terminals or from 12V to ground - do you think this is normal or would this high resistance point towards a duff battery?
The battery cranks the engine over very well. Overall I have an ECU issue not firing injectors or coils, and all checks I have performed come back OK... crank and cam sensors, grounds etc. So when I noticed that most sensors have a 12V supply that ALSO shows continuity to ground on the same wire, it makes me beleive that the issue lies around there.
Any thoughts please?
If the battery turns the engine over well, clearly the battery is fine.
Most sensors should have a 5v regulated supply from the ecu. Only very very few would ever have 12v.
So more importantly you say there is no spark, yet have checked everything.
Just exactly what have you checked for and how ?
Does the ecu power up ? Are you getting 12v at the coil and injectors ?
When cranking are the coil/injectors receiving a signal from the ecu ?
If not, have you verified crank/cam signals with a scope, and are they normal ?
the list goes on really.
What are you testing "continuity" with? It's a VERY BAD idea to put a resistance meter across a power source! Generally, you will damage your meter! (because a to measure the resistance of the target, the meter itself must have a low resistance to not affect the reading, and so a very large current may flow out of the battery and damage the meter)
Technically, of course, the battery must have continuity to ground, otherwise how would it complete the electrical circuit? Batteries have a property called internal resistance, which is the effective series resistance of the cells themselves. The way you measure it is to load the battery with a known current and measure the output voltage drop at that load. V=IR then tells you the internal resistance (generally very low for most battery systems.
For example, say you take 100Amps from a nominal 12v battery, and the output voltage falls by say 1V (to 11v) you know the battery must have a 10mohm resistance (1v = 100A X 0.01OHM)
Technically, of course, the battery must have continuity to ground, otherwise how would it complete the electrical circuit? Batteries have a property called internal resistance, which is the effective series resistance of the cells themselves. The way you measure it is to load the battery with a known current and measure the output voltage drop at that load. V=IR then tells you the internal resistance (generally very low for most battery systems.
For example, say you take 100Amps from a nominal 12v battery, and the output voltage falls by say 1V (to 11v) you know the battery must have a 10mohm resistance (1v = 100A X 0.01OHM)
stevieturbo said:
If not, have you verified crank/cam signals with a scope, and are they normal ?
the list goes on really.
A bit of background... The donor car was a Lexus Soarer with a 1JZ GTE and a R154 manual box and the recipient car was a 1994 Mazda MX5 - All of the swap has been completed, all of the fabrication done and just now need to get it running.the list goes on really.
Donor car was bought running and I drove it back from the guy I bought it from about 2 years ago so know all the bits worked OK.
So original ECU and wiring harness has been used, though stripped of any P/S, A/C, TEMS wiring etc. Upgraded injectors to 560cc Mitsubishi Evo top feeds, upgraded fuel system operated manually on a switch panel. The car is being used for Drag so has no Idle Control or O2 either (May add O2 back in), only circuits left are Crank sensor, MAP, Cam Sensors, TPS, AIT sensor, Water Sensors, Alternator etc.
My problem is I am getting no spark or fuel...
The story so far of things I've done and checked.
- Wired ECU to ensure that the B, B+, IGSW have 12V. M REL gives me 12V but I've wired the fuse box off a switch through the Main EFI Relay rather than through the key. I'm happy with this part.
- STA has 12V on crank. ECU B, B+, IGSW retains the 12V on crank, doesnt drop the voltage.
- The 2 Black / Orange wires in the loom have 12V, to injectors and Coils etc.
- Engine earths on E01, E02, E1, E1 have earths (according to continuity test on multi meter) - Earths terminate on the tab on the head near the front and both rings use the same earthing point due to it running an aftermarket inlet manifold which has no M6 / M8 female points to attach to.
- Running an Optima Red Top battery in the passenger compartment, earths onto a welded on bolt to the chassis on the trans tunnel, extra thick earth from the battery to the engine block, and small OEM earth from the head to the firewall.
- I have tried to use temporary jump leads as extra earth straps to see if this would resolve, but no.
- When activated, the ECU gives 12V to one wire on the coils, and both wires on the injectors as it should (I beleive), just no pulsing on the node light or spark to coils. Tested with a plug grounded on the rocker covers and no spark.
- Crank Sensor, Cam Sensors, Ignitor all have continuity on wires to ECU.
- Crank Sensor removed, cleaned up the end, checked the 12 point disc that it rotates with the crank, with my finger
- Crank Sensor and Cam Sensors have a resitance of around 1050 ohms which I believe falls within range.
- Receiving IGF signal from the ignitor to the ECU, which has continuity to ECU and voltage raises to 0.3 volts on crank.
- Ignitor has 12V and earth to it on the 4 pin connector. The R / Y is IGF siganl I beleive, not sure what the other wire does.
- All TPS and other sensors have 5V supply (might check this again though!)
- Checked Cam Sensors for voltage, but I didn't realise they were Resonance effect sensors.
Guess I could do with scoping the Cam and Crank Sensors?
So my thoughts are if I have havent got either spark nor fuel then it is something affecting both and I beleive you only need the Crank Sensor, at least 1 of the 2 Cam Sensors and an IGF signal minimum to crank. So in my mind that would rule out the ECU and Ignitor being bad, unless both of the are gone which I don't think is the case.
I'm leaning towards either of the following areas:
- Bad earths
- Bad Crank Position Sensor
- Battery Issue
Anyone got any suggestions on what to try next?
Thanks for your help!
I'd say it is none of the above things you seem to think.
Keep it simple.
Does the ecu power up ? Does the ecu prime the fuel pump output on power up ?
Basically those two would at least make a reasonable assumption the ecu is live and functioning.
Is there an immobiliser present within the car/ecu ? If so, do you have all the parts needed to make sure it will behave itself ?
Overall....how many wires have you cut, removed, altered etc etc ? If it isnt an immobiliser problem, you can be pretty sure it is a wiring problem.
It will not be the battery, it will not be a major earth.
Crank/cam maybe, but you'd need to do some proper testing. If the engine was running before in another car, then there is little reason it shouldnt run now.
Some live data would be handy to see if you have an rpm reading, as well as sensor feedback to see if things are reading sensibly.
Or most Toyotas will self diagnose with flash codes. Although you've maybe disturbed so much wiring etc, who knows what codes might be present now.
http://planetsoarer.com/obd/obd.htm
I assume you actually have some proper wiring diagrams for the engine/vehicle in question ? So at least you can trace/verify what they are supposed to do ?
Keep it simple.
Does the ecu power up ? Does the ecu prime the fuel pump output on power up ?
Basically those two would at least make a reasonable assumption the ecu is live and functioning.
Is there an immobiliser present within the car/ecu ? If so, do you have all the parts needed to make sure it will behave itself ?
Overall....how many wires have you cut, removed, altered etc etc ? If it isnt an immobiliser problem, you can be pretty sure it is a wiring problem.
It will not be the battery, it will not be a major earth.
Crank/cam maybe, but you'd need to do some proper testing. If the engine was running before in another car, then there is little reason it shouldnt run now.
Some live data would be handy to see if you have an rpm reading, as well as sensor feedback to see if things are reading sensibly.
Or most Toyotas will self diagnose with flash codes. Although you've maybe disturbed so much wiring etc, who knows what codes might be present now.
http://planetsoarer.com/obd/obd.htm
I assume you actually have some proper wiring diagrams for the engine/vehicle in question ? So at least you can trace/verify what they are supposed to do ?
stevieturbo said:
Does the ecu power up ? Does the ecu prime the fuel pump output on power up ?
- See my previous post about all the relevant lives getting power (B+, Batt, IGSW) on the ECU. Fuel pump is wired on a standalone circuit rather than ECU driven and is fine.
Is there an immobiliser present within the car/ecu ? If so, do you have all the parts needed to make sure it will behave itself ?
- There's no immobiliser on these ECU's
Overall....how many wires have you cut, removed, altered etc etc ? If it isnt an immobiliser problem, you can be pretty sure it is a wiring problem.
It will not be the battery, it will not be a major earth.
- Maybe it is, but my previous post which highlights continuity and earthe which all seem OK.
Crank/cam maybe, but you'd need to do some proper testing.
- I would think this is possibly one of the main causes rather than wiring. I've had the whole engine loom stripped down and know what each wiring does. I've only lost wires to do with EVAP, P/S, A/C ... nothing that I will be using again, and certainly shouldn't stop it from running.
Or most Toyotas will self diagnose with flash codes. Although you've maybe disturbed so much wiring etc, who knows what codes might be present now.
- This has still been left in, so I will try and see of it gives me a code, though the earlier non E-OBD ECU's only give about 40 codes in total, so they can be a pointer rather than the cause.
I assume you actually have some proper wiring diagrams for the engine/vehicle in question ? So at least you can trace/verify what they are supposed to do ?
Yes, I have full 1JZ manuals which is why all voltages / resistance fall within spec though the only thing I can't check at the moment is scoping the cam and crank sensors due to lack of a scope!- See my previous post about all the relevant lives getting power (B+, Batt, IGSW) on the ECU. Fuel pump is wired on a standalone circuit rather than ECU driven and is fine.
Is there an immobiliser present within the car/ecu ? If so, do you have all the parts needed to make sure it will behave itself ?
- There's no immobiliser on these ECU's
Overall....how many wires have you cut, removed, altered etc etc ? If it isnt an immobiliser problem, you can be pretty sure it is a wiring problem.
It will not be the battery, it will not be a major earth.
- Maybe it is, but my previous post which highlights continuity and earthe which all seem OK.
Crank/cam maybe, but you'd need to do some proper testing.
- I would think this is possibly one of the main causes rather than wiring. I've had the whole engine loom stripped down and know what each wiring does. I've only lost wires to do with EVAP, P/S, A/C ... nothing that I will be using again, and certainly shouldn't stop it from running.
Or most Toyotas will self diagnose with flash codes. Although you've maybe disturbed so much wiring etc, who knows what codes might be present now.
- This has still been left in, so I will try and see of it gives me a code, though the earlier non E-OBD ECU's only give about 40 codes in total, so they can be a pointer rather than the cause.
I assume you actually have some proper wiring diagrams for the engine/vehicle in question ? So at least you can trace/verify what they are supposed to do ?
Steve_D said:
Check you have wired the cam and crank sensors the right way round.
Did you say the ECU is giving a live feed to the injectors? Normally there is an ignition switched feed to the injectors and they are earthed by the ECU.
Steve
I have checked this before, I can't see how I could get them the wrong way around as they all plug in to the loom, and have continuity to the correct part of the ECU. The Injectors give 12 to both wires where one should drop to ground from the ECU as you correctly say, but it doesn't.Did you say the ECU is giving a live feed to the injectors? Normally there is an ignition switched feed to the injectors and they are earthed by the ECU.
Steve
Thanks for the help so far!
Steve_D said:
Check you have wired the cam and crank sensors the right way round.
Did you say the ECU is giving a live feed to the injectors? Normally there is an ignition switched feed to the injectors and they are earthed by the ECU.
Steve
But when the injectors are off...it will usually send 12v down the trigger wire.Did you say the ECU is giving a live feed to the injectors? Normally there is an ignition switched feed to the injectors and they are earthed by the ECU.
Steve
DO a flash code test or try and get hooked up for some live data so you can at least see if the sensors etc are connected correctly.
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