Replacement Alternator

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Re: Replacement Alternator

Postby Simon_P » Wed 18.05.2022, 20:48

Ken, as you say there are different configurations of regulator but from recollection the other sort means that the ligh is on all of the time O2 sensor or not.

I'm no expert in how it works but the logic as I understand it is.:alternator wire provides a ground when the engine is not running and the ignition is on so current flows through the bulb and it illuminates. When the engine is running and the alternator charging the voltage on both sides of the bulb is the same so the no current flows and the bulb does not illuminate.

Reading the wiki description it looks like the O2 wiring diagram is causing some confusion. It needs to be read in conjunction with the alternator wiring diagram. It is then aparant that the O2 heater is connected to the alternator by tapping into the no charge light circuit.

It appears that the no charge bulb is being grounded through the O2 heater, which would suggest that there is no/insufficient current supplied by the alternator connection.

With the O2 sensor disconnected, ignition on, engine not running does the no charge warning light illuminate fully? Or not at all?
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Re: Replacement Alternator

Postby KenS » Wed 18.05.2022, 21:59

Thanks Simon, so Mike, if you want to investigate you could totally rule out the O2 sensor by checking the heater resistance is good i.e. around 7.5 Ohm (between sensors 2 white wires, or the two diagonal pins (of 3) in the connector). If its OK, then its most likely a fault within the alternator, where it cannot support the current demand of the O2 sensor heater. As Simon says, with O2 Sensor disconnected, ignition on and engine not running, the Warning lamp should be fully lit, if its not, its another indication of a fault within the alternator.
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Re: Replacement Alternator

Postby KenS » Fri 20.05.2022, 13:49

Its been raining here all morning, so I used the time to research into the alternator regulator which controls the Charge Warning light (and powers the O2 sensor heater where fitted i.e. S2 Elans and SEs that have been modified for closed loop ).
Its not uncommon on this Forum for replacement alternators to give a constantly lit Charge Warning light. I had this problem in 2019 when fitting a new SJS alternator, I didn't solve the problem and ended up refurbishing the old original alternator with one of Simons refurb kits (which worked without problems) and put the new SJS alternator in the spares box.
So today I pulled the suspect SJS alternator from the spares box and opened it up to find the regulator marked with part number 'VR-H2005-7A'.
Checking old posts on the forum and the inter web for equivalents, I found that the original alternator was fitted with Denso regulator 126000-0430, that equates to equivalent 'VR-H2005-5H', so not the same as the part fitted in after market alternator.
Comparing the two regulators:
regulators.jpg


This shows the pin configurations are the same D-IGN-L (where D = Dummy (no connection/no sense connection)), but the L connection (Lamp) has different functionality. The original (-5H) has ability to drive a 'choke', whereas the -7A does not have that ability.

Searching the web finds that the 'choke' refers to the ability to power additional circuits eg choke relay/solenoid at start-up.

So this would imply that Elans with O2 sensor heaters, which need about 1 Amp, really do need the correct regulator VR-H2005-5H or direct equivalent. A regulator that is not spec'ed to drive Choke will probably work in an standard SE but not in an S2 or O2 sensored SE.

So I have now ordered a replacement VR-H2005-5H regulator to fit in the SJS alternator - then I will have to decide if it goes back in the spares box until needed or take the pain in fitting it just to confirm that it is a good fix.
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Re: Replacement Alternator

Postby TorqueHorse » Fri 20.05.2022, 15:39

Regardless of outcome, Hats off for the well documented deep dive!
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Re: Replacement Alternator

Postby dapinky » Fri 20.05.2022, 16:13

Ken,

Thank you for taking the time to research the issue and suggest a (well researched) fix. It is a bit of a shame that whoever fitted then regulators didn't save a few quid by fitting the right items to start with (but I suppose it was a case of what they could get hold of, and probably works fine for cars without O2 sensors......).
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Re: Replacement Alternator

Postby Rambo » Fri 20.05.2022, 16:32

Well done Ken. I now know what to order when replacing the old regulator in my alternator (orange warning light always on) My fix was a piece of black masking tape subtly placed over the offending light :lol:

Where did you order your VR-H2005-5H regulator from please?
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Re: Replacement Alternator

Postby KenS » Fri 20.05.2022, 17:26

I have ordered Ebay item 263203081541, mainly because It will arrive early next week, I don't think it will be the best quality and would recommend trying to find a better part. HC-Cargo.co.uk list part 134447 as equivalent to the Denso 126000-0430 and state that L can drive Choke, - but maybe those parts are also sourced from China and you need a trade account to purchase. Simons alternator repair kits are probably a good route since they have been proven multiple times (and on my S2), just this time I only needed the regulator for my (new) SJ alternator, not the full kit.
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Re: Replacement Alternator

Postby Rambo » Fri 20.05.2022, 21:35

Yes, me too. I have one of Simon's kits to repair one of my alternator's but just need a regulator to repair the other. Might be easier to purchase another spare kit from Simon. Then I might flog one, or both, my spares :wink:
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Re: Replacement Alternator

Postby Bryan M » Tue 13.09.2022, 18:41

I have this problem on my SE - it has replacement alternator fitted about 7 years ago and it charges fine at 14v but the red battery light remains on - is it as simple as swapping over the regulator to the correct one to put the light out?
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Re: Replacement Alternator

Postby KenS » Tue 13.09.2022, 20:53

Hi, I cannot give a straight yes/no answer - the need for a VR-H2005-5H (or direct equivalent) is when the car has an O2 sensor, this regulator type can drive the added load of the 02 sensor, so this would normally be S2 Elans, but if your SE has been modified with an O2 sensor then it to will need the VR-H2005-5H style regulator to satisfy the added load it applies to the regulator. If your SE does not have a retrofitted 02 sensor then your problem may well be due to some other issue, but still quite possibly related to the regulator since there are not many failure modes with so few connections to the charge lamp, so changing the regulator for either of the variants may well be a fix:
lampCapture.JPG

(and for reference, the 02 sensor connection to NY26B is only valid for S2 Elans or modified SE Elans:
bCapture.JPG
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