Trane XL80 No ignition 3.9 v to igniter during start cycle

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Old 01-20-20, 01:03 PM
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Trane XL80 No ignition 3.9 v to igniter during start cycle

2- 1987 XL80 Furnaces (TUD090A936A0) side by side parallel hookup, 1 furnace is fine the second stopped running sometime in last 5 days. The non running unit at call for heat the white Roger's control (model 50e47-843) comes on, vent fan starts, igniter doesn't glow, only 3.9 volts at igniter wiring from control box.Resistance thru igniter is 1.44 to no cracks. Gas never comes on, I figure it's because no heat from igniter. Need help where to go from here on troubleshooting before throwing money at it (control module). Any help would be appreciated
 
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Old 01-20-20, 01:27 PM
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Here's a link to the manual for the control which includes "blink codes" & troubleshooting. https://climate.emerson.com/document...es-4474772.pdf
 
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Old 01-20-20, 05:10 PM
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Green Led goes to slow blink red after exceeding ignition recycling. I can reset and the same sequence starts over. If it wasn't so cold I would swap control out of working furnace. But the sun is down and 15* heading toward 9* overnight
maybe I'll try that tomorrow 28 high
 
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Old 01-20-20, 06:06 PM
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igniter doesn't glow, only 3.9 volts at igniter wiring from control box.
Check it directly at the control box to eliminate igniter plug.
If still low..... the module is bad. It needs to put out 120v to the igniter when heating.
 
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Old 01-21-20, 06:40 PM
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Yep low voltage at control
 
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Old 01-21-20, 07:02 PM
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A very common problem is one of the control relays like for the inducer or igniter
gets pitted/arced requiring the board to be replaced.
 
 

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