WAIT light question

[HeisenBob]

Wait light has been an issue on my rig for some time. It is very inconsistent. The past few days, I’ll turn on the key and the wait light is off with the relay under hood staying silent. Voltage also doesn’t drop. When I start the truck, the wait light immediately comes on and the relay starts to cycle. The system cycles for several minutes like it’s supposed to until the truck warms up.

Does it sound like a weak battery? Truck starts ok unless it’s a little chilly. Then it takes about 7-10 seconds.

 

[WWRD99]

Wait light has been an issue on my rig for some time. It is very inconsistent. The past few days, I’ll turn on the key and the wait light is off with the relay under hood staying silent. Voltage also doesn’t drop. When I start the truck, the wait light immediately comes on and the relay starts to cycle. The system cycles for several minutes like it’s supposed to until the truck warms up.

Does it sound like a weak battery? Truck starts ok unless it’s a little chilly. Then it takes about 7-10 seconds.

My guess is the control board isn't getting key on power and getting power at the start position with the key...or possible bad board or the start switch on the column is worn or is out of adjustment...sounds like it wants to work but not at the right time...could check with a test light if it is getting power with the key turning on or with the start position...quick test would be hit the key to start the truck but let off the key back to run position before it starts and see if the wait light stays on. But as most will attest....weak batteries can wreak havok on these trucks so do make sure they are fully charged up!

 

[Mullaney]

Wait light has been an issue on my rig for some time. It is very inconsistent. The past few days, I’ll turn on the key and the wait light is off with the relay under hood staying silent. Voltage also doesn’t drop. When I start the truck, the wait light immediately comes on and the relay starts to cycle. The system cycles for several minutes like it’s supposed to until the truck warms up.

Does it sound like a weak battery? Truck starts ok unless it’s a little chilly. Then it takes about 7-10 seconds.

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Another good possibility is ground. It would be a good investment of your time to check there behind the emergency brake peddle. There is a small ground block that seems to corrode over time. Pulling those ground wires, scratching the wires and connectors with a small wire brush and applying some Antioxidant Paste is a good way to keep the connections clean.

 

[Barrman]

One of mine did that when I first got it. I could leave the key on with no wait light, open the hood and jiggle the wires at the connector for the glow plug temp sender on the drivers side head rear inside the valley. I would jiggle until I heard the relay click and then get back in to start it up.

I ended up replacing that connector, sensor, relay and the glow plug card. I haven't thought about it in more than 10 years now. Follow the steps in the -20 manual. Mine had that many not testing correctly every time parts. Yours might just have a loose connection as talked about in a previous post.

 

[HeisenBob]

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Another good possibility is ground. It would be a good investment of your time to check there behind the emergency brake peddle. There is a small ground block that seems to corrode over time. Pulling those ground wires, scratching the wires and connectors with a small wire brush and applying some Antioxidant Paste is a good way to keep the connections clean.

I’ll look for that one. I did the block that’s on the driver side/under the dash area.

 

[HeisenBob]

One of mine did that when I first got it. I could leave the key on with no wait light, open the hood and jiggle the wires at the connector for the glow plug temp sender on the drivers side head rear inside the valley. I would jiggle until I heard the relay click and then get back in to start it up.

I ended up replacing that connector, sensor, relay and the glow plug card. I haven't thought about it in more than 10 years now. Follow the steps in the -20 manual. Mine had that many not testing correctly every time parts. Yours might just have a loose connection as talked about in a previous post.

 

[HeisenBob]

Of those, the only item I haven’t replaced is the card.

 

[McSpeed]

mine ended up being a damaged thermal switch on the intake. Somebody must have stepped on it - even though the truck says all over (NOT A STEP) or something...but it looked okay till I wiggled the connector and saw it was broken from the housing making hit or miss connection and the same symptoms. Was an easy cheap fix.

 

[Mullaney]

mine ended up being a damaged thermal switch on the intake. Somebody must have stepped on it - even though the truck says all over (NOT A STEP) or something...but it looked okay till I wiggled the connector and saw it was broken from the housing making hit or miss connection and the same symptoms. Was an easy cheap fix.

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Well, that generally sucks.
On the other hand you got it fixed.

Best part is that since YOU found the problem and fixed the problem and paid for the parts with your money - chances are the NOT A STEP step won't ever be used as a step again.