Wait To Start Light *BLINKS*

[rvaughn801]

Twice in as many weeks my WTS light starts blinking when:



1. Truck is warmed up

2. Shift into Reverse

3. Radio, dash, lights all look fine



Stays blinking until I shut it off. Does not blink if I restart it.



This seems like an electrical problem. I searched old posts and found advice to clean the grounds. After the first WTS Blink episode, I cleaned the one that goes from the battery to the radiator support, and the one from the block to the alternator.



While I am on the topic, I am convinced my grid heaters do not work work as they were intended. The "WAIT TO START" has only come on a hand full of times, in weather so cold that I would have been better off to plug it in.



The only way to get the heaters to work is to turn the key through "ON" and almost to "START" until I hear the click. I know it will start in negative degree temps. But I cannot let the wife drive it in really cold weather and be confident she will get a WTS light.



Is there a simple fix for this?



Are the grid heaters problematic enough to be eliminated (and depend on plugging in for low temps)?



I appreciate your help.



-Rich

 

[dpuckett]

Your 89 grids wont come on til it gets to 15deg or something obscene like that. But, it should still start by the 2nd-3rd crank even then. With my slightly lowered compression (thicker head gasket, stock pistons), mine will crank about 3-4 rounds if it is below 25deg.



It sounds like you may have an ignition switch issue. I am not sure how to go about testing to make sure, but with your having to almost hit the start, and the WTS light coming and going erratically, it could well be the cuplrit, unless someone else has a better idea.



Another possibility may be your grid heat controller. Not sure where it is located, thogh below the brake master cylinder rings a bell.



Daniel

 

[JimmyDiesel]

Is there a seperate controller for the grid heaters on an 89? In my 92 they are controlled by the computer. I had a very similar problem that turned out to be the computer it-self. When my wts light was blinking, the soleniods where getting a slight pulsation of voltage (actually ground) from the computer at the same rate the wts light was blinking. also, if you let it blink long enough the heaters would actually engauge, (and the light came on steady). hope this helps.



-jimmy

 

[rvaughn801]

Turning the key past "ON" and almost to "START" makes the grid heaters cycle as though the truck was running. Since the grid controller does not give a WTS light until 15 deg, this makes it easier to start. At low temps, it will fire on the first rev but not stay running. It will start and run at low temp (without the key turning trick) if I give it a little fuel and hold the key on START past the first few ignitions.



After I posted yesterday it did the same WTS blink when I shifted into reverse. That is twice in a day, it is getting more consistent. I let it blink all the way from the store. It makes me a little nervous to think about the heaters staying on constantly - how long would it take to damage the intake if they don't cycle? I have not seen the radio and dash lights dim like they do when the heater is cycling.



dpuckett-I replaced the ignition switch a year or so ago, trying to find another problem. It was not very expensive or difficult, it would be worth trying another one.



JimmyDiesel- I will also check for the grid controller grounding the relays. From your description the coils will have 12V when the ignition switch is on, but the ground side is connected when the grid controller switches it.



I would like to change to the later grid controller, which has a legit WTS light, I think around 50 degrees. I could rig up a switch, but I hate to have any more "tricks" than needed. A momentary switch that would latch a relay for 30 seconds would probably do the trick. A momentary switch could be cycled once or twice to get started, and then once or twice once running if needed.



Thanks for your help.

 

[phillips5]

I have one off my 90 you can have. I can mail it to you. I am parting out my 90 . The engine trans and rearend are sold but the grid heater controler is still there. The relays are there also.

 

[Paychk]

89 FSM Diesel supplement states the WTS light will flash when the controller doesn't read the temp. sensor. Check the wire harness from the controller to the sensor for breaks or bad/corroded connections.