Trane XE 70 no longer heating

The heat from my Trane XE 70 stopped working. When I turn the thermostat on, I get the initial click from the relay but no flame and no click click click click........ So I dug up the schematic (haven't looked at a schematic since the Air Force, 30+ years ago) and I think I found a voltage issue at the pilot relite (White Rodgers 5059-41), which is getting 24V at T1 but nothing at T2. It seems that the 24V that should be going to T2 should be coming from the gas valve but I'm not sure. Any suggestions would be helpful. Thanks in advance!

 

After further digging (and realizing a forgot A LOT about A/C circuitry), it appears that the voltages on the pilot relite are supposed to be 0V (common/neutral) at T2 and 24V at T1. So does that mean the pilot relite module is bad? If I pull off the orange wire off the pilot relite module and try to read the voltage off the lead in the middle of the blue plastic piece, should I get a high voltage reading if it's good?

 

Welcome to the forums.

Put the high voltage lead back on the module. Measuring there will destroy a meter.
You need to have 24vac on the two power tabs when the thermostat calls for heat.
It looks like when the module gets power.... so does the gas valve.

You should post a picture of the wiring diagram or the full model number of the furnace which is found on the ID plate on the side wall near the burner.

 

Thanks for the response, Pete!

 

Blue is common. There should be no problems with the common line.
White is the W/switched 24vac power.
Clip one meter lead on the common/blue line. 24vac is applied to W(1) from the thermostat.
Check for 24v on both sides of safety stat 3.
If ok.... check for 24v on both sides of fusible link 4.
If ok.... check for 24v on both sides of fan/limit switch 5.
If ok.... check for 24v on T1 of igniter module.
If there it should also be on the gas valve 7.

 

I appreciate you taking the time to draw that up for me. Thank you very much! I have 24v at all the points you said to check. No spark. Coincidentally, I already pulled off the igniter module, thinking it might be the issue. I may have jumped the gun doing that but it's a learning experience and I'm ok with that.

 

You can connect 24vac to T1 and T2 to test.

 

And when I do hook it up, what should it do? Start clicking?

 

Ok, I figured it out the correct way to wire it. When I connected it, I heard a really faint clicking (3 clicks) and then nothing.

 

When you connect the spark module it creates sparks from the high voltage spike to ground.
I usually use an alligator clip lead connected to module ground to check for spark.

 

I pulled the ignition module out and wired up some leads to it. The first couple of times was very faint clicks for a few seconds then nothing. Then absolutely nothing was happening after a few more attempts. I came back a few hours later and tried again and it started working! Somehow, it must have "woke up". Put it back in the furnace and all is well again!

A special thanks to Pete for the assistance!

 

Good job. If that spark module starts acting up again...replace it

 

So the old ignition module stopped working. Ordered another one (used) and it worked until tonight. I turned the heat on and no heat. I went to the furnace and shook the ignition module and it worked. But for how long....so I was wondering if there is a modern ignition module (new) that will work for my furnace? Thanks in advance!