Hi all, some of you may have read the "alternator burnt out thread"....

Well, I`ve taken the beat (MasterAce Surf - 1991) to a new mechanic. He has had a look and due to the following symptoms, doesn`t think there is anything wrong with the alternator or regulator (both `new` 2nd hand ones)...
When the car is cold, it charges up fine. As it warms up the Xmas lights and beep come on intermittently (only for a second at a time to begin with). When the car is warm enough the lights and beep are constant, and the alternator isn`t getting any `excitement`.

The mech checked the lead that goes into the ALT and there wasn`t any current, so he thinks it`s an electrical fault further up the line. Now he needs to try and track it down. I`m sending him all the relevant wiring diagrams from the archives (dash, charging etc), but if any of you have ANY advice or insight we really need it.

The mech has checked the 3 big black fuses and they seem ok btw.

for your and future reference here is what I gleaned and abridged from the archives as to possible faults/remedies:


- try checking the 'CHARGE' fuse which you will find in a small plastic box below the centre of the dash. If this is the problem then your battery will be going flat.

- the fuses are below the glove box..also when u lift the seat at the back near the drivers seat there are fuses there. the first two fuses nearest the drivers door just pull out, but here is the sneaky bit the remaining three fuses are bolted in,to get access to them first unbolt the fuse box from the body then at the top and bottom or front and back there are 2 flip up covers to remove each fuse you must undo the top and bottom bolts, I recommend that you disconnect the battery first coz if you fry the wiring it will all have to be replaced and your other half will kill you! take one fuse off at a time obviously make sure you have new ones. If your alternator is not charging the battery i think you will find the fuse has blown, it is the 120amp fuse i think the middle one, but i would if you have gone to all the hassle of getting this far you might as well change them all.

- The final point is that without the IGN circuit being live there would be no excitation supply to your alternator which is what kick starts it into life to charge.

- More likely earth of shorting probs. Clean any earth body contacts, check wires for shorts is the best I can say. Could try remove replacing fuses sometimes works.

- My problem was the circuit breaker, which he fixed by inserted a pointed screwdriver in the hole of the pin hole circuit breaker and reset it ! Problem solved the circuit breakers are in the normal fuse box rectangular with rounded ends polished silver tops and a small pin hole.

- I have got it sorted out by removing the glove compartment and pushing the multi plugs back in securely. this may be worth noting for other owners, these plugs can and obviously do at times
- work loose.

- When the previous person looked into the problem they found some wires under the dashboard had melted together.

- alternator had a problem with the rotor.

- The problem was the positive battery connection. There is a green wire in a black shroud which had corroded and broken contact. reconnected and all was fine.

- All three is probably an alternator/ no charge problem. The dash does it's "check bulbs on turnon" thing if charging stops. Suspect a loose connection or sticky/worn brushes.

- I also have the lights-on warning signal on permanently with the ignition and lights off - the only remedy is to leave the door open slightly (I suspect there is a short somewhere but cant find it).

- Check the fuseable links- either beside the battery or under the drivers seat.

- On the live battery terminal, there are 2 (I think) connections other than the main one. One of these was loose. I reconnected these wires and the problem disappeared.

- check your battery terminals there is some small wires that go to the posative terminal they had broken reconnected these and a presto no more unwanted warning lights.

- Fuse boxes : One under the drivers seat, by the rear heater motor but it only has about 6 big fuses in.

- FUSE BOXES: One under the dash, right in the middle. Fuses relays and circuit breakers all together. Sit in passenger front seat, its above your right foot. Just behind Cool Box (if you have one).

- believe your problem is related to the magical 100k km figure which is when Toyota say you should replace the timing belt. To clear the warning there should be a reset button.

- turned out to be a slipping fan belt.

- Might be worth getting the charging circuit check, but if it's only intermittent it may not fail for a while yet.

- I took off the battery leads again and had a real good look and saw some of that lovely green corrosiony stuff on the +ive terminal connector.

- That might point to an earthing fault.

- are all the fan belts on and not loose, look at the battery (on flood behind drivers seat pull back carpet and undo inspection panel)are the connections good , get a volt meter and set on DC 12 VOLTS put meter between + - battery terminals and you should get and reading of 12vdc then start her up and at 2000rpm you should see the reading go up to 14.2vdc if you dont it may indicate a fault on charging circuit, if you do get 14.2vdc then I would look more carefully at the battery (how old is the battery)take it to a car battery shop and they will short circuit test it and tell you on the spot if its any good.

- It still sounds like the "charge" fuse below the dash is blown...

- we found the problem,the cables behind the fuse box(behind drivers seat) were melted together.

- there is lots of information in the engine manual, part No RMO25E. It costs less than a tenner and can be ordered from your local Toyota dealer.

- Had same symptoms, turned out to be the wire that takes the charge to the battery was corroded and poor contact at the battery terminal.

- It could be that you have two problems here.1 - either a failing relay such as the power main relay or ignition main relay or a short or bad earth in that area, which could explain the intermittent electrical failures. 2. If the alternator isn't charging as according to your garage, and you have had it reconditioned then yes the external alternator regulator may be at fault.

- (#15401) Storm, 15 Feb 05 11:28

Mo disrespect, but if your mechanic can't faultfind a simple charging system, you need a different mechanic- or better still an auto electrician. The same style of reg was used in many Toyotas (as well as some Nissans and Daihatsus)between 1968 and the early '90s so it's not an unknown quantity...

So the field coils lose excitation when the car warms up. OK then, what about the supply from the regulator? Have all the wires been checked for continuity during the fault situation? Can you confirm a supply to the regulator, for that matter. Both "charge" and "ignition" are involved, their feed coming off the ignition switch. As the engine isn't cutting out, we can assume that the ignition switch is OK.

My guess is that the replacement reg you got is a duffer...
- (#15401) david miller, 15 Feb 05 15:05

If it`s the replacement reg, how come the fault only appears once the engine is warmed up? Until then it is all charging nicely and no loud constant beeping. Weird.

- (#15401) Storm, 15 Feb 05 16:15

Thermal fault in the replacement reg? Dunno. It's a pretty simple circuit, any auto spark worth his salt should be able to debug it in an hour. (sorry to be so dismissive but I've been faultfinding circuitry from simpler than this up to fuel injection systems and indeed laboratory and cardiac eqpt for the past twenty years and don't have a lot of time for non-specialist mechanics)

Just to confirm, when the lights come on, it's *definitely* not charging? Some Toyotas control the "no-charge" light through a relay. If the relay was failing, the lights would come on but the battery would still charge...

You say he's checked the lead going into the alt and there's nothing on it. Which one? The big one from the battery, or one of the wires in the 3- or 4- pin connector?

There's only six or seven connections to/from the reg, so it shouldn't be difficult to check which one is changing when the fault occurs.

- (#15401) david miller, 16 Feb 05 01:49

These circumstances occur frequently. Last month I was dealing, indirectly and unsuccessfully, with a Townace doing the same thing - warms up then lights on and no charge - and I recognise the posts that Storm has researched and helpfully collated.

It seems to me that competent auto electricians are few and far between, at least in some areas, like diesel, aircon, stainless exhaust specialists, or even import-insurers. And then those good auto sparks have plenty of customers to fill their hours and can afford to turn away a Townace where they will spend an hour or more to even get near, say, the alternator connector (and put things back afterwards).

As auto electrics/electronics get more complex I assume such problems just get referred back to a main dealer who diagnoses by substituting sub-units .. and bad connections lead to a write-off?

I wonder if someone with a working system should remove the relevant fuses in turn and report what the exact symptoms are, and perhaps probe into the regulator connector and report what voltages normally appear there. This data may be a start for owners, or even electricians, facing this situation. Although I've studied an alternator, and even run one on my bench, as yet I have found no documentation on the regulator, e.g. which pin does what.
- (#15401) Dave Mason (Sussex), 16 Feb 05 03:34

Unfortunately, the info we have doesn't apply to the alt/ reg in the import Townie, as far as I can tell. All the diagrams in the Russian manual refer to a mechanical reg whereas the (unique to townace) reg is electronic.
In all my time and miles, I never had a need to even look for the reg in mine. But I think I'll be under the dash of Kevin's at the weekend so I'll try to have a squizz at the reg while I'm there.

I believe that the reg however *is* identical in operation to the likes of the Lucas NCJ400 or 408 and I've got terminal ID and colour codes for them.

If anyone has opportunity to be under the glovebox before me, would you be good enough to post or email me the wire colours and connector type (two rows of three spades I believe?) and I'll see if I can translate them.

- (#15401) david miller, 16 Feb 05 04:10

Sorry about that big graphic. Was just trying something out!

I just went out to the car park and looked at my regulator. Hands still thawing out. Probably the cold made it harder to get the glove box down, the trick seemed to be to fully disengage the left-hand "catch" before trying the other one. Regulator is clearly visible on right though console plastic obstructs access. I've never even looked there before.

Removed the 10AF bolt holding it in and could then release connector, though loom is very tight and wire colours very hard to see among shadows. Marked 27700-64061 (and 126000-1340).

Yes, it has 2 rows of 3 x 0.25in spade type pins. Pin markings and connector wire size/colours:
"IG" - thin/Black +white stripe?
"B" - thick/White+red stripe
"S" - thick/White+Blue stripe
"L" - thick/White +black stripe?
"P" - thick/Blue
"F" - thin/White
Securing bolt connects to metal surface marked "E"

My next step would be to ponder these markings against what data is available an then prepare a 6-way extender loom to be able to make measurements under operating conditions - but not today!

- (#15401) Dave Mason (Sussex), 16 Feb 05 07:25

Cheers guys, I`m glad this isn`t an isolated incident. Hopefully between you techies and the mechanic we can sort this problem out. If not, I`m afraid the beast will have to be sent to the scrap-yard.
I`ll keep you updated with what the mechanic (Dave) says. He knows of this forum and Ace Archives so he may even add comments himself.

- (#15401) Storm, 16 Feb 05 08:02

Dave, that appears to be close the the Lucas NCJ400. I'll be back later with more info...

- (#15401) david miller, 16 Feb 05 08:13

Now this is by colourcode and/or Lucas terminology only:

IG= ignition controlled live
B= battery
S= centretap of stator winding- ie the "star" of the three phases
L= earth
P= most likely live
F= field coils (rotor)

It's interesting to then see how this ties in with the circuit diagrams we have- spacie, ruskie townie, RM025E etc etc.
the mechanical regs in those diagrams go:

B= battery
L= no charge lamp via "charge" fuse
IG= ignition controlled live
N= voltage sense/ centretap of stator
F= field coils
E= earth
S= supply to internal reg (if fitted)

So, once again the japanese colourcode differs from the norm- White/black is Toyota's standard convention for earth, but in this case it *seems* to go to the warning light or relay...

- (#15401) david miller, 16 Feb 05 11:02

I should add that it's at times like this I don't miss the townie at all :p

- (#15401) david miller, 16 Feb 05 11:03

Ace Answers' two Wiring diagrams, Instrument panel, show two connections from the charging system to the "dis/charge" warning lamp, which has a diode in series with it. One of these connections ( #11), when pulled low, puts on the oil and coolant level warning lamps as well, via diodes - presumably the oft-reported "3 lights on" situation.

Is this definitely different from the "all lights on/Christmas tree" situation? and how might that be caused?

The "high" end of the "dis/charge" warning lamp is connected ( #10) to the charging system. Simply to the "Charge" fused supply?

The apparent fault indications are:
#11 high, ( #10 hi or lo) no warnings
#11 low, #10 low, oil and coolant level (2) warnings only. Some kind of charging system warning - apparently failure of the "Charge" fused supply? (if that is indeed what #10 is connected to.)
#11 low, #10 high, 3 lights on, dis/charge warning on as well. Some kind of charging system warning - but evidence that the "charge" fused supply is intact.

So diagnosis may depend on exactly which lights are on, is the dis/charge/battery light on? are the oil and coolant level warnings on? are any more on? (other than door open and handbrake).

Where are these two connections ( #10 and #11) likely to fit into the alphabet soup - L,N,S,P,F above? Could be found out by cautious testing.

- (#15401) Dave Mason (Sussex), 16 Feb 05 11:43

Once I got home to look in the Russian manual I realised how the Charge fuse is connected which clears up some of my queries above.

I've updated the schematic at the bottom of the Alternator page in Ace Answers to show how the fuses, warning light and regulator connect with the alternator, as far as I can tell. Next thing is for someone to fill in what goes on insdie the regulator, or at least what to expect at its terminals.

- (#15401) Dave Mason (Sussex), 16 Feb 05 14:17

The important thing to note here Dave is that the "no charge" lamp has a series diode too. None of the other lamps can therefore affect the operation of the "no charge" one.

Can't confirm on this particular system, but it's normal for the field coils to be excited through the warning lamp- remember the bodge with the old Lucas alternators of changing the wattage of the warning light to alter it's cut-in voltage?. Now, Toyota have a habit of using a relay to isolate the warning lamp circuit from the alternator (look at RM025E), but that shouldn't affect fault-finding.

the no charge light is indeed just live at one end. the other end is taken low by the alternator (substitute relay coil for light if so fitted...) I'd say it'll be "L" or (if the colours are unconventional) "S" that operates the light, but a lot depends on whether the light is actively controlled by the reg or brought to ground by a couple of extra diodes in the alternator (or even by just reading the voltage in the centre of the stator windings.

Again, pp CH-3 of RM025E is a good reference.

I think the circuit actually installed in the townies that we see is a composite of the two that we keep seeing on diagrams here- take the diagram for the internally IC reg'ed alt in RM025 and divorce the regulator from the rotating device, and I reckon you'll be pretty close to it...

- (#15401) david miller, 16 Feb 05 14:25

An important difference from RM025E CH-3 is that our alternator's field coil is internally connected to +ve, not to ground. I measured this and the Russian manual agrees.

I've just added more detail to www.townace.com/ig/igaltwir.gif

- (#15401) Dave Mason (Sussex), 16 Feb 05 15:00

yet another attempt to get a link right - I hope

- (#15401) Dave Mason (Sussex), 16 Feb 05 15:02

Looking more like it. But the stator is without doubt three phase. I'll warrant then that the blue wire P is the centretap.

I seem to recall only three wires in the round connector at the alternator tho, not four?
- (#15401) david miller, 16 Feb 05 15:46

4 stator phases was the only way that I could explain what I found in the rectifier unit, see RM025E CH-16, but I agree I've never seen reference to a 4-phase one. However it doesn't affect how it works.

Stator winding resistance was so low that I couldn't determine if the P wire was connected symmetrically. I drew it as a centre-tap until I found p394 in the 85-96 Russian manual (which is for internal IC regulator but with same lettering). Again it doesn't affect how it works - I presume this is the only electrical signal that says, "the engine/alternator is rotating (and the alternator is excited and working)".

p405 in the R-manual shows the bulb test feature extended to 6 other warnings - so I'm guessing that whether you get "3 lights on" or "all lights on" could depend on which model/year you have.

3-wire alternator would be for internal IC regulator (as p394) with IG S and L connections only, earth via chassis. External reg includes earth for a return path for the significant excitation current - how much would you expect that to be? a fraction of an Amp?
- (#15401) Dave Mason (Sussex), 17 Feb 05 02:03

No Dave, *my* CR30 had a round plug (on a trailing lead) with THREE wires, then the additional main battery lead- which was white IIRC.

Obviously different models will have different lamp-test modes- Model F in some countries has a test button.

Field current depends on load- minimum (to excite the alt) is a couple of hundred milliamps- warning light current, in fact. But 12v straight into the field would likely be about 5A, I'd guess. Maybe a bit more, maybe a bit less, but that order of magnitude.

As I said previously, the townie's circuitry is a bit of a hybrid. Now, the question I've always asked is why they didn't just put an internal reg in? Probably no more than a cooling issue as the cover on the rear of the alt appears the same for both internally and externally regulated "internal fan" alts. (notice there's no fan on the pulley of the townie's alternator?)

Did you perchance meter the wires at the reg with it disconnected to verify our guestimates?

- (#15401) david miller, 17 Feb 05 02:28

At the bottom of the Russian diagram there's a round 3-way plug called up for the internal-reg alternator and a not-referred-to 2x3 6-way like on my external regulator.

The only measurements I've done are on an alternator that someone brought me "to test". I'm inclined to investigate further on my own working 'Ace but obviously don't want to do damage. External reg does have the advantage of moderate access to 6 test points.

To go further I need a better mental picture of how the system is likely to work. My only background is with moving contact-type regulators.

Is the field current likely to be controlled linearly or switched mode? That diode in the alternator could be just to catch overswing or it could be a flywheel diode for switched mode.

If "S" is the primary analogue voltage sensing input, and IG is the request to enable charging, why bring "B" to the regulator? Maybe just habit or as a test point. Or I wonder if the "L" fault output is fed by a load of logic that checks for reasonable voltages on B, P, S as well as IG.

The basics would seem to be that L is pulled low when IG is high and there is nothing on P. Excitation current is drawn into F when IG is high but controlled by comparing S with some reference voltage.

Remembering that the original fault is intermittent, after warm-up, we're still left with damaged regulator as the obvious cause, possibly a poor connection on the P or F wires. Bad connection or fuse anywhere else wouldn't stop charging, unless the regulator requires a minimum voltage on S to enable it.

Removing the regulator, starting the engine and connecting a 5W, or perhaps 20W, bulb between F and earth ought to get a servicable alternator charging - detectable by increased battery volts or headlight brightness?

- (#15401) Dave Mason (Sussex), 17 Feb 05 04:06

Yes, there is a 3-wire control connection to the externally-reg'ed alt.
Field current is likely to be linear, I've never seen anything else.

Why so meany connections to the reg? A very good Q. They may be measuring a voltage drop somewhere in the loom and inferring load from that- in motorcycle practice, Kawasaki at one time sensed charge voltage from the taillight circuit to hold the voltage up when the lights were turned on.
Actually, this is a possibility- why else would they require such heavy wiring for a "sense" connection?

yes, your test should indeed confirm the worth of the alternator.

- (#15401) david miller, 17 Feb 05 04:17

Given that Aces generally have such thin wiring where you wish it was thick I was surprised how thick the wires to the regulator were, even F when I learned how small the excitation current is.

But the explanation may be to do with the fusing, and this is a reason for caution during testing. Under fault conditions B, P and possibly S, could pass considerable current before a fuse (or part of the alt. in the case of P) blows, and this should happen without the wire melting. These are the thicker wires but it doesn't explain why L is a thick wire.

- (#15401) Dave Mason (Sussex), 17 Feb 05 04:29

Hi all, just to let you know that this is all totally over my head (I`ll build you a po or do a website but this... .yikes!), but I`m sending all the posts on to Dave the mechanic.
Cheers again.

- (#15401) Storm, 17 Feb 05 06:19

Over my head too I'm afraid but, what a credit to those knowledgeable and helpful contributors who are going to so much trouble helping all of us. I don't need this splendid and very comprehensive information at the moment but, no doubt, the day will come . .

- (#15401) John Davis (Leics), 17 Feb 05 06:32

If anyone has a "dead" external regulator of this type that they'd be prepared to donate to science, email me with the circumstances of its demise and I might be interested in having it/some posted to me to compare with my own, long may it work. I may be able to specify a straightforward test procedure (1) for the external regulator and (2) for the rest of the system via its connecting cable.

- (#15401) Dave Mason (Sussex), 17 Feb 05 07:00

Hi,

Its a long shot and unfortunatley I can't remember the exact details but I had a fault with my alternator that followed the classic all lights on thing, mine did turn out to be an alternator failure as the regulator had gone as had one of the windings. However I do remember when trying to diagnose the fault something about if you have a faulty temp sender it can cause you alternator problems. I assume this is because its linked to the istrumentaion wiring that tied into the lighting circuit that in turn is linked directly to the alternator.
If this is true then it could explain the failure as the vehicle warms up??

Might be a wild goose chase and I'll see if I can find the info I was looking at but it may be something to go on.

Justin.
- (#15401) Justin, 17 Feb 05 07:42

Hi all,
Got a call from Dave today. He`s been reading through all the material I sent him from here and the archives, and he`s finally tracked it down to the alternator itself. I can`t remember all the techie things he just told me, but basically he took the alternator out and tested it at various revs (or whatever), and the charging got progressively worse until it wouldn`t charge at all (which explains why it was charging, then intermittent, then not charging at all). When tested at a static rev it tested fine.

So it seems these Alts have a fault sometimes which is intermittent, and common to at least the 2 that I`ve had so far.

He said he can get me a brand new alt at £170 + vat (not a toyota one) or a toyota one at @£300.

All this time and it was the alt after all (it seems... will confirm when he`s replaced it).

Thanks for all your excellent help and research on this. Hopefully if anyone else has the same symptoms in future they can have a pretty good idea of what is wrong and how to fix it.

- (#15401) Storm, 1 Mar 05 07:25

Good to have some feedback on this thread, Storm. Just yesterday I got round to extending the wiring loom on my '91 Ace so that I can tap into the regulator and alternator connections whilst the system is operating normally. Initial voltage measurements this morning confirm everything that I've published in Ace Answers > Dashboard & Electrics > Wiring. I plan to disconnect a few things and document what the symptoms are, in the hope that will make fault diagnosis easier.

- (#15401) Dave Mason (Sussex), 2 Mar 05 03:55

Replaced the alternator with another 2nd hand one (about £100 inc postage from www.vanspares.co.uk ).

All fine now.

Will be selling the van in a few months as we are emigrating to Aus.

- (#15401) Storm, 12 Mar 05 03:30