Engine/Transmission (1998.5 - 2002) Wait to Start 10 sec delay

[farrview]

What else is energized with the wait to start light aside from the heaters? My WTS wasn't working so I wired the heater relays to a manual switch on the dash. This has been working fine, I just hold the switch for what seems long enough and the truck starts right up.

But I just put in new batteries and the WTS decided to start working again, however it doesn't come until 10 seconds after the ignition and of course, the truck won't start until the WTS at least comes on. So what else is activated with the WTS as I want to wire that directly to the ignition switch. That way I won't have to wait 10 seconds to restart the truck after its been running.

 

[JLandry]

I recall reading about similar WTS lamp behavior like this over the years here in the forums, and I'm pretty sure replacing the ECM solved the problem in at least one case... maybe more. That suggests it's some kind of internal hardware failure in the ECM or possibly a bug which creeps into the software.



Have you tried reflashing the ECM software?



John L.

 

[SnoKing]

So the Wait to Start light is controlled by the temp sensor under the drivers battery, right? Check the connection of that sensor. Did the old battery leak and cause issues with the sensor?? I just installed my second set of new batteries this last week and saw the sensor this time! It is a button type device under that battery.



For what it is worth, OEM batteries lasted slightly over 5 years, and the 72 month Pacific Battery replacements lasted 6 years and 4 months. Do they have a death timer in these batteries? I ended up back at Pacific as Costco did not have the correct batteries.



SNOKING

 

[JLandry]

So the Wait to Start light is controlled by the temp sensor under the drivers battery, right?

The WTS lamp is controlled by the ECM. Now the BTS (Battery Temp Sensor) may be one of the many inputs the ECM considers when deciding on when to energize the intake air heaters and illuminate the WTS lamp.

From the service manual:

The wait-to-start indicator gives an indication to the vehicle operator when the diesel engine intake air heater is energized in its preheat operating mode. This indicator is controlled by a hard wired input to the instrument cluster from the Engine Control Module (ECM). The wait-to-start indicator Light Emitting Diode (LED) receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (St-Run) circuit whenever the ignition switch is in the On or Start positions; therefore, the lamp will always be off when the ignition switch is in any position except On or Start. The indicator LED only illuminates when it is switched to ground by the input from the ECM. The ECM will turn on the wait-to-start indicator by pulling the wait-to-start indicator driver circuit to ground each time the ignition switch is turned to the On or Start positions. The indicator then remains illuminated until the ECM detects that the air within the intake manifold is the proper temperature to ensure reliable and efficient engine starting, until the ECM detects that the engine is running, or until the ignition switch is turned to the Off position, whichever occurs first.

The ECM continually monitors the intake manifold air temperature sensor, the Manifold Absolute Pres- sure (MAP) sensor, and many other vehicle conditions to determine when the wait-to-start indicator should be illuminated. For proper diagnosis of the wait-to-start indicator, the ECM, or the inputs the ECM uses to control the wait-to-start indicator operation, a DRBIII scan tool is required. Refer to the appropriate diagnostic information.

Assuming there's nothing wrong with any of the inputs to the ECM or a wiring problem (which would likely cause a diagnostic trouble code), then the ECM is likely faulty.

John L.

EDIT 1: Thought you might find this interesting...

EDIT 2: From Blue Chip Diesel's troubleshooting tips:

The other strange one is when the truck doesn't start until you see the “wait to start” light come on or go out, or it comes on when driving and a drivability issue appears, this has necessitated an ECM repair or replacement.

As these trucks are getting older, and only in the last year or so, I am now rarely finding a bad ECM instead of bad VP44. The good news is their symptoms are unique so far! At least one of the symptoms described above have been common to all ECMs that I have found to need repair or replacement, SO FAR. The only way to diagnose an ECM in my experience is to try a replacement, or borrow one from a friend. I have had many customers do it this way, so I feel confident you won't hurt anything, but remember one thing PLEASE. When installing the test ECM, be SURE to ground it to the engine FIRST, before connecting the big plug. This prevents any problem from static electricity getting into the ECM which can blow away the computer inside. It doesn't seem to matter what year the test ECM comes from, whether or not the old or replacement ECM came off an engine with or without a crank sensor, to fix the problem of erratic RPM, or a dumb “wait to start”' light. Yes the test ECM may set codes, but if it runs better, then you know a replacement or repaired ECM is in your future.

 

[farrview]

I have had the WTS problem for several years. During that time I also had to replace the ECM as it quit working altogether, truck wouldn't start. The WTS problem existed with the first ECM and was not changed with the replacement. I have also replaced the sensor and checked the continuity of the wires to no avail.
It now is presently working but with a ten second delay and at some point it will quit working again as it has many times before. When it is working with this delay, the truck cannot be started until the WTS is activated regardless of the temperature. When it again quits and doesn't come on at all, the truck can be started immediately when the ignition is engaged. I then will hot wire the heater relays and manually run them.
What I would like to know is what else is activated with the WTS. Is it the lift pump? If it is then I would rewire it so that it is activated by the ignition switch and not have to wait for the WTS delay.
Kind of irritating when you shut the engine off and then have to wait 10 seconds before it can be started again. Doesn't help that I have a very short attention span and really hate waiting!

 

[SnoKing]

So you have installed a new IAT sensor? SNOKING

 

[JLandry]

So you have installed a new IAT sensor? SNOKING

That's exactly what I was going ask next.



John L.

 

[SnoKing]

John, so a read up on the sensor under the battery, it is tied into Alternator and charge rates. My bad! SNOKING

 

[farrview]

What is the IAT sensor?

 

[SnoKing]

Intake Air Temp. It is behind the Map sensor near the rear of drivers side of the engine kinda under the intake manifold. SNOKING

 

[farrview]

I have replaced the IAT sensor and checked the wires for continuity. All appears to be working correctly. The WTS works however it is not engaged until 10 seconds have passed after turning the ignition switch to the on position. Until that time the engine will not start.

 

[SnoKing]

Maybe you have a Central Timer Module issue. One of the outputs is Engine Enable (PCM). Time to have Dodge plug in their DRBIII. SNOKING