WTS Lamp will not come on.  Truck still starts.  Manifold heaters do not come on.  Has a hard time starting in the cold without block heater(start up) Runs good. I usually wait for instrument light to turn off before starting....  WTS LIGHT has not been working for 5 months.  Any ideas appreciated...

I let it sit for two weeks. Batteries went dead. Tried to start and the lift pump stayed on. Charge the batteries and that problem stopped. 

So when you Key on the WTS does not come on even for a second?  

No light ever

 

Any P0381 error code?

I do not have a scanner.  I have done the test  on the dash and no codes were present.  The wait to start light never went on with this test.

You going to have to stop at a local part store and have them plug and read the codes. 1999 trucks don't have any means of reading codes. There is no key trick. you might be talking the cluster test but that light remains off in the cluster test because it's controlled directly by the ECM and not the cluster. 

OK will do.  I will return with info....thanks for your help!

The ECM triggers the WTS light regardless to tell you the ECM is booting up, if it does not come on the ecm hasn't booted, so it shouldn't in theory run, less mike is right and you have a p0381 code, which is saying your WTS light is burnt out.  Then you need to look at IAT and ECT sensors or grid heater relays.

Possibly... 

 

P0381 code would tell there is a bulb problem or wiring problem to the bulb. There could be other codes like P0380 or P0382 codes which the grid heater relay have issues and not firing. 

 

The only other thought which I would call a long shot is the WTS circuit of the ECM is damaged. I've never heard of that happening. 

Isn't the WTS light a replaceable bulb in the cluster? If so, the bulb is most likely missing or burnt out.

7 hours ago, 99_Cummins_4x4 said:

Isn't the WTS light a replaceable bulb in the cluster? If so, the bulb is most likely missing or burnt out.

 

P0381 code would verify the bulb and save you a ton of work if you just check the codes.

 

 

No codes found.  This truck has never thrown a code in 19 years.(check engine) I did check the relay to the intake heater. No power.....but engine was warm.  I do notice a power draw after it starts like that is when it is going on.

20 minutes ago, MuleMan said:

This truck has never thrown a code in 19 years.(check engine)

 

Remember some codes like P0216 code does NOT trip the Check Engine light. 

 

Do you have power to the main terminals of the relays? (Large black cables)

 

 

Edited November 28, 20186 yr by Mopar1973Man

On the battery side yes.

I've got to ask another wild question do you have a live data tool? if so take notice to the IAT temperature. If the engine coolant temperature and the intake air temperature don't match then more than likely the IAT sensor could be bad. It's possible for the IAT sensor to fail within specs and not trip an error code. But... The intake air temperature reports wild temperature could be very high and prevent the grid heaters from coming on. 

 

This poses another thought too. I know my High Idle Kit has the MPG mode which fools the IAT to show 143°F at key on the grid heaters will not fire at all. Then after starting the grid heaters will cycle in. I wonder if the IAT circuit has a homebrew resistor added as a fooler and causing the grid heaters not to fire. This could be seen with the live data tool as well it will report 143°F typically regardless hot or cold. 

Edited November 28, 20186 yr by Mopar1973Man

 Do you think I still need to check the light bulb itself? How hard is it to get to the bulb in their instrument cluster? 

Edited November 28, 20186 yr by MuleMan

Remove the dash bezel. Then you might have to drop the steering column to remove the cluster but it held in by 4 screws. Once the 4 screws are removed you should be able to pull it out of the dash socket. Like mine won't come out unless I drop my column slightly to gain clearance.

My cluster comes out with out loosening the steering column. But I might have had the column ignition cover off, cant remeber.

So I checked the grid heater relay at cold start.  They did not come on between key on and start.(30 seconds) The relay did send power to to the heater for about 4 seconds on each leg intermittently but not at the same time.....is that normal??

Have not got into the cluster yet to test the bulb

While on the subject of connections:  My stock radio works but has no display(for quite some time 3 or 4 years now) Sometimes when it is cold the display will show.  Has anyone had this problem? and is it internal or some connection on the outside of the unit?

Sounds like the ECM is damaged on the grid heater circuit. It should of INSTANTLY power up both the grid heater relay on the key ON ran for about 15 seconds. Then clicked off. It should have had +12V power at the smaller wires. 

 

Try something disconnect the little wires on the grid heater relays and then turn the key on and see if it sets a P0380 code and P0382 code this will tell if the ECM can even see the relays. 

 

Another passing thought. The Battery temperature sensor and the IAT sensor both control grid heaters. If the battery temperature sensor is damaged or reporting high temp then the grid heaters might be disabled. 

Edited November 30, 20186 yr by Mopar1973Man