> Jensen Healey & Jensen GT Tech > Ignition > Ignition light stays on and voltmeter shows less than normal voltage. What’s up? |
> Jensen Healey & Jensen GT Tech > Ignition > Ignition light stays on and voltmeter shows less than normal voltage. What’s up? |
| Moderated by: Greg Fletcher | ||
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Tim Murphy Member 
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My 74, VIN 17303 ran good for a week. Now the ignition light stays on, the voltmeter takes about 5 minutes to get just barley into the white, i.e., about 12 volts. Normally this past week the ignition light goes off after starting and revving the engine, my voltmeter has been at 14 volts, i.e., past the vertical line at 13 volts. Help me before I get my shotgun and blow my car to bits. Other things that may (or may not) be related: I know my hazard switch is bad and I have a new one. The center consul is till out and all the wires just piled together. I put on a new alternator belt and is was squeaking upon heavy acceleration even thought I thought the belt was tight enough. First, am I driving on just the battery? Where to start in trying to diagnose the problem? |
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Mark Rosenbaum Member 
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If the alternator isn't producing electricity, then you are indeed operating only on the battery. This can be verified by clipping a charger to the battery. If the battery accepts a fairly heavy charge for several hours, then there's something wrong in the charging system. OTOH, if the battery is fully charged when you start, then most likely you have a problem in the warning light wiring and another problem in the voltmeter or its wiring. (Simultaneous multiple failures are quite rare but not entirely unheard of.) Most likely your problem is (1) a dead alternator, (2) a wiring problem in the engine bay, or (3) a shorted cell in the battery. If the car cranks and starts normally, then unclean battery connections can pretty much be ruled out. (1) The alternator is best checked by dismounting it and taking it to one of those parts stores that does free tests. As it happens, JH alternators are still commercially available, so if yours is bad, there's a very good chance the store will either have a replacement in stock or can get it quickly. Alternately, you may wish to have yours rebuilt, or switch over to a single-wire alternator. (2) Make a visual check of the wiring. Check the ground wire between alternator and engine block for connection and condition. Make sure the connectors that plug into the alternator are seated, and that there are no wires broken off just inside the connector, then unsnap the plastic cover over the junction on the heavy positive battery cable, and make sure the thick brown wires that goes to the blade connectors there are all firmly seated and that there is no corroson present. (3) Using a hydrometer, check the specific gravity of the electrolyte in each cell. The reading for every cell should be about the same; gross differences may indicate a fault. If the battery is not fully charged, then charge it for a couple of hours and recheck the specific gravity. If (a) the specific gravity in each cell has not risen noticeably, or (b) there are still gross differences between cells, the battery has failed. When a JH is being particularly stubborn, a brisk talking-to, or the threat of using French- or Italian-made parts, will often shame the beast into submission. But if you find that you must use the shotgun, a decent appreciation for the proprieties requires that you use only ammunition manufactured in the UK. A single shot applied directly to the base of the distributor will give a quick, clean kill. :^} |
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Tim Murphy Member
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Hi Mark. I am going with my gut feeling and your ‘diagnoses at a distance’ and have ordered a new alternator. I checked the battery cells and they were all good. When I charged the battery it took 10 amps and took two hours too get down to taking a 2 amp charge. Hence my conclusion that I needed a new alternator. I think I fried my a alternator when I installed a new engine wiring harness I got from Delta Motorsports. It came without any directions and I tried to install it according to the wiring schematic. Nothing worked. After two weeks, I called Delta and explained my problem. The response I got was "Oh, you have a Lucas alternator, those are wired different then the schematic. I will send you a copy of how to wire it, should get there in 5 days or so." Man, I am glad the FCC doesn’t monitor phone calls, because I would have been fined $6.3 million for all the F’ing, AsHols and can’t believe this Sht’s I used. I was sooooo mad, a $130 part and they didn’t send me directions. I buy a clock at the 99 cent store and I get directions, I buy a bottle of shampoo and there are directions on the back. I lost 3 weeks of expensive garage time and a have a fried alternation because they were to lazy to make a zerox copy and send it to me with the part. I purchased a NEW alternator on eBay, item number 7917087784. It cost $60, 50% LESS then Deltas 1996 price list of $90 for a rebuilt alternator. Before I purchased it I sent the seller and email and got an immediate response: You asked: "Cost of shipping to Huntington Beach, CA 92646? Is there a core charge? Also, auction states new (not rebuilt) lucas alternator, is this correct? Thanks, Tim Murphy" Hi Tim Thank you for your inquiry. Yes this is a new Lucas but is made in the plant in India There is no core charge. Shipping UPS ground will be 11.47 Thanks Wayne Will post again after I install the alternator. |
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Mark Rosenbaum Member
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Tim, any 'diagnosis at a distance' is just a lucky guess unless (a) the person with the problem accurately describes the pertinent symptoms, and (b) the diagnostician knows what he's talking about. I suspect that we both did our parts properly here, so mutual pats on the back are likely to be appropriate. Charging for 10 amps to begin with, and dropping down to 2 amps after a couple of hours, is entirely typical of a partially discharged battery, so a dead or inoperative alternator sounds most plausible. Over the past 30 or 40 years, I've seen dozens of alternators and voltage regulators, both new and rebuilt, that were defective out of the box. My first thought would be that your case was another such. I'm not sufficiently familiar with the differences between the Delco and Lucas alternators to have a valid opinion as to whether an inappropriate wiring harness could cause damage. While modern electronics gadgets are remarkably reliable, there are still ways to damage or destroy them almost instantly, and few of these are apparent to human senses. The true cause -- wiring harness, installation error, defective part in alternator, component 'infant mortality', incompetent rebuild, or something else entirely -- may never be known. Alas, it's been my observation that Delta's folks may occasionally forget that not all of their customers are as familiar with JHs as they are. This is hardly unique to Delta, rather it occurs to almost anyone who's been deeply involved in any single field for multiple decades. Since Delta has harness alteration instructions, they're obviously aware of the situation, and I'd have expected a copy to be included with each affected (Lucas) part. But mistakes do happen. Even when the business model includes plans, processes, and procedures to reduce such mistakes to the lowest practical level, there will still be oversights -- just a lot fewer of them. India seems to have inherited or acquired the designs and/or tooling for a lot of British legacy products. This might be considered a reward, the Brits' last revenge, or possibly both. In any event, if (a) the original directions on how to make a part are complete and accurate, (b) they follow these directions, and (c) they use the correct materials, then the new parts should be at least as good as the originals. Given the quality of some of the original parts, that may not be saying much. However, the components, materials, and manufacturing processes that are commonplace nowadays are so much better than what was available in the 1970s, that one can reasonably expect a vastly improved part quality, and it's my understanding that this is precisely what's occurring. One last note: use a straight edge (ruler) to check the alignment between alternator and water pump pulleys when you install the new alternator. Sometimes it's necessary to use flat washers as shims to get everything properly lined up. The lifespan of the water pump and alternator tend to be longer if the fan belt does not apply any fore-and-aft forces to the pulleys. |
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Tim Murphy Member
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Update on Alternator and Installation I sent the money for the New, made in India Lucas alternator via paypal and was emailed the next day that it had been shipped. It arrived about a week latter and was complete (with front pulley, fan, bearing, etc.) as pictured in the eBay BIN auction. Installation went smoothly (well, as smooth as any JH repair can go) and everything fit. Started the car and everything was back to normal, i.e. ignition light goes out after a few seconds, voltage slowly climbs to 14 plus volts. Life is good. Special Note: The Lucas alternator is wired differently then the JH wiring diagram which is for the original (on 73 cars) Delco alternator. The JH wiring diagram shows a 10 gauge black wire going to ground. To quote from the Jensen Service Bulletin Delta Motorsports finally sent me: "NOTE: The 10G black ground wire may be taped or removed. DO NOT connect this wire to the alternator or severe damage will occur....Dealers should be aware that damage to alternators due to incorrect connection is not a warrantable item." Nice too get that information 3 weeks after I received the engine wiring harness. |
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