It appears that the switch in the intake manifold on my 90 that activates the wait to start light has failed. Appears to be "open". The grid heaters do heat and cycle off, but after starting, the wait to start light continues to flash. The heaters do not continue to heat. It acts the same way if I just pull the plug from the switch. If I short the connector, the wait to start light will not light nor will the grid heaters work.

I'd like to replace the switch and have searched this site, the web and called the local Dodge dealer. I cant seem to find a reference for that darn switch. I know I can put in a manual switch, but would prefer to have the automatic system working again. I live where it is routinely below 15 deg F in the winter.

Can someone provide a part number and/or a source for that switch?

Thanks so much!

 

Check the sticky. Under electrical, "what are all these wires doing on a mech truck." be sure the look under non intercooler, I think you are look for what is labeled as b. I am glad I checked the sticky I was about to tell you where mine is, without knowing it moved on an inter cooled truck.

 

Hi Thiss...thanks, yes it is part labeled "B" in the pic in the sticky.

What I need is a part number so I can buy one. The local Dodge dealer is clueless and I figured if I could provide them with a part number, perhaps they could find it! Better yet, would be a replacement like a Niehoff or some other number. (By the way, I called Niehoff about the TS81281 shown for the intercooled trucks and it is no longer available).

 

I got mine from Napa.

 

Try part #4429547 Sensor,temp.(Int.Manifold) (Thermister) (Stamped3613547) per factory parts manual.

 

Thanks guys!

Thiss - I didnt even try NAPA, but I sure will they are likely less expensive there than a dealer part! Do you recall just what you asked them for? I'll try to explain it using the right terminology.

Dodgenstein - thanks so much. I'll call the Dodge dealer tomorrow and see how many million they want for a #4429547!

Bruce

 

Is this it?

here


Mark

 

Hi Mark,

I don't think so. That one says "Coolant Temp Sensor" so I'm assuming it's for the water jacket rather than the air intake manifold and probably is for a temp gauge or some such application.

Thanks for checking tho....

Bruce

 

Sorry about that...Here is a good test procedure

Intake Manifold Air Temperature Sensor Test

(1) Disconnect the wire harness connector from the intake manifold air temperature sensor.
The sensor is located on the top of the intake manifold and to the rear of the air heater.
(2) Test the resistance of the sensor with an input impedance (digital) volt-ohmmeter. The
resistance (as measured across the sensor terminals) should be less than 1340 ohms
with the engine warm. Refer to the Sensor Resistance (OHMS)—Intake Manifold Air
Temperature resistance chart. Replace the sensor if it is not within the range of resistance
specified in the chart.
(3) Test the resistance of the wire harness. Do this between the powertrain control module
(PCM) wire harness connector terminal 21 and the sensor connector terminal. Also
check between terminal 4 to the sensor connector terminal. Repair the wire harness
as necessary if the resistance is greater than 1 ohm.
Temperature Resistance (ohms)
°F °C Min Max
-40 -40 291k 382k
-4 -20 85k 108k
14 -10 49k 61k
32 0 29k 36k
50 10 18k 22k
68 20 11.3k 14k
77 25 9.1k 11k
86 30 7.3k 8.8k
104 40 4.9k 5.8k
122 50 3.3k 3.9k
140 60 2.3k 3.7k
158 70 1.6k 1.9k
176 80 1.1k 1.4k
194 90 860 970
212 100 640 720
230 110 480 540
248 120 370 410

from here



http://dodgeram.org/tech/dsl/trouble...niford_htr.htm


Mark

 

Thanks again Mark. While that is for a 2nd gen truck, I'm sure the diagnostic routine would be the same. I'm quite sure my sensor is bad and have just been trying to figure out how to get a new one. Your link to the NAPA coolant sensor tipped me off to searching the NAPA site and I came up with this

http://www.napaonline.com/Search/Det...+50022+2022043

which may be the right part. I'll have to check at NAPA and match it up with my old part. This one is listed for 89-at least 97 and listed as an "air charge temp sensor" which in gas engines is associated with fuel mixture. From doing some reading on the web, it appears that the function (to vary resistance with air temp) is the same and so maybe Cummins used this part for a different purpose, ie to turn on/off the heater grids.

If so, they are cheap. I found the same part from Standard Motor Products - AX36 (I think they make it for Echlin) for under $10. I'm anxious to find out if it is the right part.

Thanks again.

 

I'm bored with nothing better to do...

http://www.clessieonline.com.au/Cles...lass=PartsList

put the cummins part number in and they show to have it, has a pic too. Are you sure that is for the later cummins? I was sure it was for the early...Mark Just checked you're right, I'm having a bad reading day

 

I think you found your boy from napa. Air charge temp sensor for 29 bucks from echlin. Not to be the barer of bad news, but Faith just answered someone with the same issue and it you need a new PCM. When my air charge temp sensor took a pooh it gave a fault code and I flat lost the grid heaters. They never engaged and the wait to start light never made me wait, it simply acted like it was warm enough.

 

Thanks guys for all the help. I ordered one of the NAPA parts. I'm betting (hoping too) it's the sensor and not the PCM.

Bruce

 

The intercooled PCM is a different animal. On a non-intercooled brain box, the flashing WTS light is actually a diagnostic design feature.