Electrical HELP...WTS light flashing constantly

[BertM]

WTS light flashing constantly

Working on my dad's '89 D250 2WD auto, bone stock, 101K. Truck built 9/88, one of the very first off the assembly line. On start-up, all indicator lights come on, go off as normal, 5-10min. or so of driving, WTS light begins flashing, not flickering. Usually continues until you shut the engine down. Has been doing this for a while with no? ill effects. No current to heater grid when light is flashing. All connections look good, no apparent melt downs of the coils. Truck is starts and runs fine, although not very cold down south. I'm stuck, what do I check? TIA

 

[paccool]

I spent some time this morning before work looking through my 93 manual. If the charge air temperature sensor reading is below minimum or above maximum, the wait to start light will flash on and off.



I tried to find what the min and max were but couldn't . I'm sure it is in the book, just a matter of figuring out where. Anyway, sounds like the sensor could be causing this to happen. This is located just behind the inlet air horn into the top of the intake manifold.



Also, I am assuming the 89 is the same as the 93. We all know what the word assume means though!



Hope this helps.

 

[BertM]

Thanks for the tip. That sound like I may be getting a "high" temp signal since the falshing begins after running for a while.

2 questions: 1. ) The sensor on this engine is not on top of the intake manifold by the air horn like the later trucks. I cannot find it anywhere. Where the heck is it? 2. ) When I find it, how do I check it. Resistance? TIA

 

[Philip]

The min and max readings are in the gasser section. They both use the same sensor for temp.

The max an mim readings are determinded by the outside temp. for a 50 degree day it is a min of 17,990 max of 21,810

This reading is taken across the pins of the sensor itself.

In a 93 service manual it is page 8D-13



In case your wondering why the gasser section on this reading. Remember history. This was the time Dodge almost went out of business. They were using any parts they could across all lines of vehicles. They allready had this sensoe in the supply chain. They just reused it on the 91. 5 trucks and up.

 

[Philip]

It is located in the intake plate behind the air intake tube. There are two sensors towards the back of the plate. You need the one closest to the intake tube.

 

[BertM]

Philip, Thanks for the reply, but, I have no sensors mounted in the intake plate, none in the heater grid and none in the air horn. I know the sensor you are describing for the later trucks (intercooled?). This truck was built in 9/88, one of the very first Dodge Cummins. I can't find any sensors anywhere in the intake system. I did notice a sensor at the very back of the head on the drivers side. Could this be it or water temp. ?

 

[Philip]

If you have a digatil camera get a pic of the top of the motor on the intake area. If the sensor your talking about goes into the intake plate area it is probably the one yopu want. If it goes into the head itself. It might be the water temp.

Some of you nonintercooled guy's jump in here and tell us where the sensor is at.

 

[BertM]

Philip, only two sensors I see are on the side of the block, drivers side, below the injector pump and on the back of the head on the drivers side. Disconnected battery overnight to try and reset computer. Reconnected battery. Unplugged the 2 wire sensor on side of block and switch key to run position. Only got warning light for ABS and Brake, no WTS. Plug sensor back in same deal. Garage was warm though. Somebody has got to know how this curcuit works.

 

[BertM]

OK, nobody knows where the IAT sensor is on this truck, but this is getting stranger! Noticed while driving truck tonight, got WTS system check on start-up drove 1-2 miles in neighborhood, WTS starts flashing. Stop, unplug sensor below thottle linkage, no effect on flashing light, replug sensor. Shut-down, restart, no WTS, USE LEFT TURN SIGNAL, WTS BEGINS TO FLASH. Hum?, Shut down, use left turn signal while stopped, WTS begins to flash again. What!? Pull in garage, shut-down, click key to run position, WTS solid for 15 seconds, loud clunk from relays when it shuts off, truck cranks, try left turn signal again. No WTS flashing. What the heck is happening here? This truck has a plug-in trailer lighting harness and the fuse for the back-up lights was blown when I started fooling with it. Fuse has been replaced. Truck also had electric trailer brakes installed at one point but they have been removed. Could a flasher problem create issues with the computer or WTS curcuit?

 

[Philip]

Could a flasher problem create issues with the computer or WTS curcuit?

Not likely. But a bad dash ground could. All eclectrical items have to have a good ground. If a circuit has a ground problem. It will go to ground anyway it can. If it has to go threw another circuit it will. The WTS light flashing with the turn signals would be an indication of a ground problem with the dish or the whole body.



On my 93 the dash grounds are behind the the plate to the left of our radio. There is a metal support behind the plastic dash cover. The wires ground to this on the back side.



Also clean the ground wire coming off of your battery neg to the body. It is grounded to the raditor support.



The sensor below the injection pump is oil pressure.



When you unplug the sensor on the head. What does your temp gage do?

 

[dusthomps]

IAT Sensor (Non-Intercooled)

I'll try to give you a hand here Philip...



Bert, on the intake horn there is a throttle support bracket. The IAT sensor is in the middle of this bracket. On the non-intercooled models it's actually called a thermistor. IAT sensor sounds so much better. It is pretty much located driectly down from the crossover tube. Just take a look at how your throttle linkage is held on and I think you'll see what I'm talking about... if not, just drop another line.



Philip, hope this helps you out a bit.





Dustin

 

[dusthomps]

Bert... I just read the IAT Sensor thread... looks like you've already gotten the advice I just gave you... If there is just a pipe plug in the manifold, I'm not sure what to tell you. I looked through my 89 service manual and everything I've read says there should be a sensor there.



Dustin

 

[Philip]

There has to be a sensor somewhere. What type of pipe plug. Is it an allen head or a regular square head. Dodge only uses allen head or square head pipe plugs. You say there are no loose plugs around the throttle linkage area. Is there and tape that does not match the factory tape on the other harness? Like someone cut off the wires and taped the stubs into an harness.





How would you like to go on a drive about an hour or so North of Indy.

 

[BertM]

Philip, The plug where the sensor should be has an insert 1/2 square. Looks like a Diff. oil plug. It appears to have black paint on it that matches the engine. No new tape on the harness and it doesn't look like the original tape around the black corrugated wire tubing has been disturbed. I will check closer though. The only empty plug is a 2 wire plug out of the group near the grid relays. Plug has a cap on it. White and red wires.

 

[Philip]

If you do not have a cruise controll the two wire plug there by the grid relays is for a vacuum switch that mounts behind the left hood hinge.

 

[BertM]

Philip, Correct, no cruise. There is a sensor somewhere. This morn. , below freezing, 15 sec. or so on the grid heater and easy start. Still got WTS flash while driving. I beginning to think there may be some gounding problem as you suggested. Through AM radio tuner, get extremly loud whine(based on radio vol. ) that corresponds w/ engine speed. That doesn't sound normal. Will check the Body/Chassis ground and report back.

 

[Philip]

A whine in the radio might be a bad diode in the alt.

Unplug the alt for a short drive and see if the whine goes away.

 

[BertM]

Philip, I think I found the sensor. 2 Wire sensor in the side of the head, drivers side, betweend the #4 and #5 valve covers. Way up underneath the intake manifold. Very difficult to see. It is a water temp sensor, when I pulled it out, out came the coolant. When disconnected, Grids fire for 15 secs. WTS begins to flash immediately after relays click off. Does this when engine cold and hot. Do you guys have this sensor. Part reads, CECO, USA25K, 3613547. Am I on to something here?

 

[BertM]

Reading back on Jdurhams posts, this is the same part # he had for the air intake temp. sensor. Just talked to Cummins, he lists it as an air temp sensor also. Should I consider moving this sensor to the "normal" location? I check the wiring harness, slightly too short to move to the intake horn but that can be fixed. Any suggestions? $36. 60 for the part.

 

[Philip]

The heater grind shouldn't run off of the coolant temps sensor. Does your temp gage stop working when you unplug this sensor?



If you temp sensor works with this sendor unhooked. It is for air intake temp only. I would move it from the coolant circuit to the place it should be mounted.



If you do move this sensor. If you have to lenghten the wires. Do not use stakeones and butt splice them. Solder these wires and use heat shrink tubing. It might stop a lot more headaches later on from a bad connection from a stake on being out in the weather.