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PV, 120 (Amazon), 1800 General Forum for the Volvo PV, 120 and 1800 cars |
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Over-Reading TachoViews : 459 Replies : 5Users Viewing This Thread : |
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Nov 12th, 2021, 16:51 | #1 |
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Over-Reading Tacho
My tacho over-reads by about double,, how do I get it sorted? By the way I need the real dummies guide here, better still an explanation that helps me understand when I take it in to the garage for them to fix.
The car’s a 1962 P1800 with retrofit electronic ignition- basic not programmable.. How do I check which Gen is fitted? Ive tried to understand this site; http://www.sw-em.com/Smith's%20Tacho...mmercial_sites Is there a cheap/ easy fix I can try first? There was some mention on the above site of a sender behind the grill- what am I looking for and how does that work? Is that easy to change and likely to be the issue? I don’t want to find the garage send the Tacho away for “repair” when there is some detail about the P1800 we need to be aware of. Anyway enough ramblings- so if you could help with some ideas please keep them simple. Many thanks Simon Having re-read the link the Tacho looks to be a Gen 1 as there is no “4 Cyl Negative Earth” on the face. Last edited by Simon703; Nov 12th, 2021 at 17:33. |
Nov 12th, 2021, 18:43 | #2 |
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It's not set to 6 or 8 cylinder is it? A lot of these rev counters are adjustable for number of cylinders
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Nov 12th, 2021, 19:10 | #3 |
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Thanks. Any ideas how I check?
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Nov 12th, 2021, 21:02 | #4 | |
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Nov 12th, 2021, 23:23 | #5 |
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Nov 13th, 2021, 02:17 | #6 |
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Simon;
If it the original Gen 1 Tach, and it shows signs of life at all (although a generous reading), you can consider yourself quite lucky (most Gen 1s have died a miserable death, and factory recommendation for repair was to replace with Gen 2 unit) ...knowledge about the inner workings of the remote sensing module located in front of the Radiator is scarce, but I expect that the electrolytic capacitors within suffer from the same drying-out issue that the Gen 2 Tachs, with internal circuit also suffer from, with your symptoms as a possible and likely effect. I'd first try adding and external 10,000uF filter Capacitor on the Tach power line, and reporting any change in the operation. All else I know and can recommend is on the linked SW-EM page you have visited. Good Hunting! |
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