hornsfan10609
Certified Mazda Tech
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- 2003.5 Mazdaspeed Protege x2
Plus these cars are known to have corroded battery cables that cause many different electrical problems.
Starter problem? Help!
- Thread starter curls
- Start date
I think I have two problems occurring -- a bad starter START signal (wire/connection on the B/Y or B/L wire from the igntion switch to the starter solenoid), AND a bad alternator/charging system.
I'll get the car started first (first problem) and then tackle the alternator/charging system second.
Out to the garage I go...
I'll get the car started first (first problem) and then tackle the alternator/charging system second.
Out to the garage I go...
I cleaned the ignition signal wire @ the solenoid, with brake cleaner, and VOILA, she started like a champ!
However, the problem with the alternator is definitely there. I am NOT reading above 12V when the car is on (measuring the POS batt to any grounded area of the engine bay only gets me 11.9 V or lower... it drops over time, meaning the alternator is not charging the battery at all and that is why the car doesn't act strange for a few minutes (once the battery drains low, the car acts all f'd up as it doesn't have the electrical power it needs).
I tensioned the alternator drive belt and that did nothing.
However, the problem with the alternator is definitely there. I am NOT reading above 12V when the car is on (measuring the POS batt to any grounded area of the engine bay only gets me 11.9 V or lower... it drops over time, meaning the alternator is not charging the battery at all and that is why the car doesn't act strange for a few minutes (once the battery drains low, the car acts all f'd up as it doesn't have the electrical power it needs).
I tensioned the alternator drive belt and that did nothing.
Measure alt voltage at several points to see if you have a resistance somewhere. Measure voltage from neg post to neg terminal (will tell you if your terminal to batt is good, should be ~0v)
Measure from Alt cable lug in the fuse block to neg batt post.
Measure from neg post to Alt + terminal.
This should show your area's of high resistance if you have them. If the alt is bad it will be less than 14v at the terminal otherwise its in the cables/connections.
Someone just posted a thread where their alt + cable burned in two due to corrosion.
Measure from Alt cable lug in the fuse block to neg batt post.
Measure from neg post to Alt + terminal.
This should show your area's of high resistance if you have them. If the alt is bad it will be less than 14v at the terminal otherwise its in the cables/connections.
Someone just posted a thread where their alt + cable burned in two due to corrosion.
"Someone just posted a thread where their alt + cable burned in two due to corrosion."
Corrosion in the wire did not cause the wire to burn out, it was overloaded or it had a short circuit. Resistance in wiring reduces current, reducing current doesn't burn out wires, see my response about ohms law in the other thread.
Clifton
Corrosion in the wire did not cause the wire to burn out, it was overloaded or it had a short circuit. Resistance in wiring reduces current, reducing current doesn't burn out wires, see my response about ohms law in the other thread.
Clifton
I've seen 220V industrial plugs burn up because a poor wire connection inside, ie high resistance. By your theory it should have never done so, so why is that? For one, Voltage and current are hardly constant; rather power is not constant.
Use ohms law in the power version where P = IR^2 If current remains constant but resistance goes up, the power dissipated increases exponentially.
The alternator is a current source not a fixed voltage supply. Take a wire normally running at 1ohm resistance and take it to, I dunno, 10 ohms resistance from corrosion. If the alternator is trying to put 10 amps into the battery, the good wire is only dissipating 10 watts where as the 10 ohm one is dissipating 1000 watts.
Its been years since I've thought about this stuff so correct me if I'm wrong.
Use ohms law in the power version where P = IR^2 If current remains constant but resistance goes up, the power dissipated increases exponentially.
The alternator is a current source not a fixed voltage supply. Take a wire normally running at 1ohm resistance and take it to, I dunno, 10 ohms resistance from corrosion. If the alternator is trying to put 10 amps into the battery, the good wire is only dissipating 10 watts where as the 10 ohm one is dissipating 1000 watts.
Its been years since I've thought about this stuff so correct me if I'm wrong.
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Got the new alternator in, things were looking good. (The alternator was tested at a parts place and failed miserably and sounded pretty bad doing it. It was done).
Until the car decided it didn't want to start again. I'm certain that there is a problem with the ignition switched wire somewhere. I tested it again and its only giving 11.2 volts but the constant wire to the starter is giving a solid 12.2 volts. Somewhere, either by design or by a fault somewhere, the ignition switch wire is losing about 1v. Whether this is enough to not trip the solenoid, I'm not sure, although I guess it would seem to be since if I jump the 12v constant to the switched terminal, the starter whirs like it should. I'm not good with the Ohms law thing -- how would a wire drop 1V with a fairly constant source of power (the battery)? Increased resistance, from an area of corrosion or partial break?
I took a look under the dash and the black/blue wire that my wiring diagrams say is the ignition signal wire, was also reading 11.2 volts. This was even before the aftermarket alarm.
Would a partially corroded wire actually cause a voltage drop like this? I couldn't find the ignition wire coming out of the alarm brain (if it even goes through it... I found an open-ended plug that was switched with the ignition). If I were to run a new wire from BEFORE the alarm I think this might cause problems with the alarm, wouldn't it?
ARGH. Any extra help greatly appreciated guys!
Until the car decided it didn't want to start again. I'm certain that there is a problem with the ignition switched wire somewhere. I tested it again and its only giving 11.2 volts but the constant wire to the starter is giving a solid 12.2 volts. Somewhere, either by design or by a fault somewhere, the ignition switch wire is losing about 1v. Whether this is enough to not trip the solenoid, I'm not sure, although I guess it would seem to be since if I jump the 12v constant to the switched terminal, the starter whirs like it should. I'm not good with the Ohms law thing -- how would a wire drop 1V with a fairly constant source of power (the battery)? Increased resistance, from an area of corrosion or partial break?
I took a look under the dash and the black/blue wire that my wiring diagrams say is the ignition signal wire, was also reading 11.2 volts. This was even before the aftermarket alarm.
Would a partially corroded wire actually cause a voltage drop like this? I couldn't find the ignition wire coming out of the alarm brain (if it even goes through it... I found an open-ended plug that was switched with the ignition). If I were to run a new wire from BEFORE the alarm I think this might cause problems with the alarm, wouldn't it?
ARGH. Any extra help greatly appreciated guys!
F it. I just talked to my dad and his suggestion makes sense: Wire in a single pole single throw automotive relay near the starter, using the starter constant as the 12V source (which I know gives full battery voltage, not hampered by a problem somewhere), and the ignition switch wire as the signal (since the 11.2v is more than enough to trip the relay, it shouldn't become a problem if the wire does corrode or deteriorate more in the future... there's lots of headroom here).
Does that sound plausible?
Does that sound plausible?
when you jumped it, did you use an aligator clip? With sharp teeth?
I would thinkg that 11.2v is enought to actuate the solenoid. Clean everything with 150 grit sand paper and make it shine.
Put your volt meter on the solenoid spade if you can while you crank it. There may still be a large voltage drop between your the connector and the starter which goes away with an aligator clip.
I would thinkg that 11.2v is enought to actuate the solenoid. Clean everything with 150 grit sand paper and make it shine.
Put your volt meter on the solenoid spade if you can while you crank it. There may still be a large voltage drop between your the connector and the starter which goes away with an aligator clip.
I used a screwdriver w/ insulated handle.
I'll check the voltage drop but since I see the drop (11.2v) at the ignition wire under the dash, at the fuse box, and at the starter solenoid... this tells me it isn't a problem with the connector at the solenoid, its somewhere upstream. I could be wrong though.
Will the relay idea work? Frankly I'm fed up with this car problem. LOL.
The alternator is a regulated voltage source, mazda specs it at 13-15 volts, assume 14 volts. The current is variable based on demand. P5 alternator current 0-77A @ 2000 rpm.
This calculator is interesting to play with.
http://www.sengpielaudio.com/calculator-ohm.htm
If you use 14 volts and 1 ohm the calculator reads I-14 amps, P-196 watts.
using 14 volts and 10 ohms the calculator reads, I-1.4 amps, P-19.6 watts.
Using your example 10 amps and 10 watts, voltage is 1 volt, resistance is .1 ohm. 1000 watts gives a voltage of 100, resistance is 10 ohms. Not possible with a properly working alternator.
I agree the heat in a circuit must be dissipated within the circuit, good wiring helps get power to the motor or other component where it's needed.
Sorry for robbing "curls" thread to discuss theory.
Clifton
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- -- 03 P5 / 23 CX-5 --
Not sure if this matters or not at this point but my replacement alternator had a big red sticker on it that said NOT to test the alt while off the vehicle. I get voltage readout from the ecu via obdII connection on the laptop verified by the volt readout from the radar detector plugged into cig lighter & also by testing different points in the wiring as stated above. Yes, radar detector has a voltage readout for some reason.
My replacement had a sticker (two of them actually) saying not to test without the proper "P/D" plug. It did not say never to test the alternator out-of-car, just not without the proper plug.
Regardless, it isn't the alternator that is preventing the starter solenoid from catching...
Not to beat a dead horse but you did clean the battery posts and terminals right?
Also check the distribution block (fuse box) in the engine compartment, perhaps there's some corrosion in there too causing the voltage drop way upstream.
I gave the power formula wrong, its P = RI^2 as V = IR so current is squared not resistance. This won't be nearly as dramatic of a power difference. If the alt can crank out 70 amps then I would assume the system was in a state of constant "overload" as it had to over come the resistive contact. And yes I'm sorry for hijacking your thread too.
Also check the distribution block (fuse box) in the engine compartment, perhaps there's some corrosion in there too causing the voltage drop way upstream.
I gave the power formula wrong, its P = RI^2 as V = IR so current is squared not resistance. This won't be nearly as dramatic of a power difference. If the alt can crank out 70 amps then I would assume the system was in a state of constant "overload" as it had to over come the resistive contact. And yes I'm sorry for hijacking your thread too.
Yes I cleaned the terminals, and it was a new battery so if there was corrosion there, it'd be long gone by now.
I spoke w/ my friend who works on cars occasionally, but more importantly, is an electrical engineer (industrial). He wants me to check the resistance of the key tumbler itself - should be nil or very very close to it. I'll check that next, as well as use a jumper cable to link the battery (-) and engine block, to rule out the engine block ground wire.
If all else fails, a 40A relay is being sourced and I'll be hooking that up this weekend and calling it quits on working on this problem for a long long time, hopefully.
I spoke w/ my friend who works on cars occasionally, but more importantly, is an electrical engineer (industrial). He wants me to check the resistance of the key tumbler itself - should be nil or very very close to it. I'll check that next, as well as use a jumper cable to link the battery (-) and engine block, to rule out the engine block ground wire.
If all else fails, a 40A relay is being sourced and I'll be hooking that up this weekend and calling it quits on working on this problem for a long long time, hopefully.
IT'S FIXED!!
I installed the relay and crimped and wrapped all connectors, secured the ground well, and mounted the relay to an existing bolt on the firewall (bolt from a small bracket). Fired up like a champ! I'm now getting 14.3 volts when running so the new alternator is working perfectly, and the starter works like a charm.
Thank goodness this saga is over... it was really getting on my nerves.
Thanks to everyone who provided assistance!!
I installed the relay and crimped and wrapped all connectors, secured the ground well, and mounted the relay to an existing bolt on the firewall (bolt from a small bracket). Fired up like a champ! I'm now getting 14.3 volts when running so the new alternator is working perfectly, and the starter works like a charm.
Thank goodness this saga is over... it was really getting on my nerves.
Thanks to everyone who provided assistance!!
drgnzadiel101
Member
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- 2002 mazda protege5
haha i wonder why i never read this before? it had happened on my accord. the relay blew. glad you got it fixed!
Curls, I'm having the same initial symptoms as you are, except for I think my alternator is ok because the battery was (and still is) strong leading up to the no-start situation. Can you explain your solution a bit: what relay and connectors and where? And you mounted it on the firewall inside, so basically you replaced the circuit running from battery to ignition to solenoid?
