I'm installing an alarm/remote start unit in my truck (see specs in my signature) and need to located the Wait-to-Start Light wire and the Tach wire. The wiring guide for my particular truck says:

"Diesel Tachometer wire is Gray/Black and Wait-to-Start wire is Orange/Black (-). Both are located on the center of the firewall (2 black plugs with wires in the top plug without the white insert). Tachometer wire also found at the ECM on passenger side firewall in connector C-1, pin 8."

Can y'all help me figure out how to find these two wires? I wouldn't even know where the ECM is located inside the cab if I wanted to check there. If y'all could tell me some easy places to get to either (or both) of these wires, or even just how to get to the ECM inside the cab, I'd be VERY appreciative.

 

Your Dodge "PCM" is located on the passenger side firewall, directly behind the air filter housing. This is the one you're probably interested in. The Cummins "ECM" is located on the drivers side of the engine, right in front of the lift pump. The Dodge BCM (Body Control Module), is located under the center of the front seat. It controls things in the truck you can't imagine, such as the brake lights.

Chris

 

I also installed a remote starter in mine, but my RS unit has a 'Diesel' setting. This gives the unit a 15 second delay between turning on the power, and actually starting the engine. I tapped into the tach wire, under the hood, in the big wire loom that runs along the firewall. It is a grey wire, with a black stripe. I tapped into it just to the right ( passenger) side of the valve cover. Sorry I can't help you with the WTS wire, as it was not needed for mine. Send me a line if you want a picture. Good luck.

 

What does PCM stand for? Is this PCM located in the engine compartment or inside the cab? Do you think the Wait-to-Start wire could be found here?

Hmmmmm...a picture would be wonderful if you knew of one. Also, is this ECM not accessible from inside the cab? I understood the DEI wiring diagram I have to say that you can get at it from inside the cab.

 

Go to Autozone or Pepboys or one of your local autostores and get a service manual. I bought a haynes. you will find a wealth of knowlede as well as pictures to help you through mods and service.

 

Stat, according to the wire diagrams I have the wait to start should be pin 37 ORG/BLK in the ECM, The engine speed sensor should be pin 8 GRY/BLK in connector 1 of the PCM. Hope this helps

Rick

Oh Yeh, in the PCM the wires are looking at the plug, plugged in, lower right corner should be #1, #2 should be fused ign switch output light green and black

 

Can I not get to the Wait-to-Start wire in the wire loom running along the firewall up top near the windshield or over behind the air filter box in the PCM? I ask because I don't know how to get to the ECM.

 

I am trying to get the pictures for you but it was too cold this morning to be outside. The ECM location is real easy.
1: Locate your fuel filter housing.
2: Standing on the drivers side, look at the FF housing. The ECM is located against the engine block, between the FFH and the starter. I found it easier to locate it from underneath. You will see a black metal box with a ton of wires plugged in on one side, this is your ECM.

 

I concur with JYD . Additionally, there are two 10 pin connectors on the instrument cluster board. the WTS light on the cluster is controlled by the org/blk wire noted earlier and is on pin 8 of one of those connectors. It's the only one of that color, so it should be easy to find. The pinout looks like this from the back of the connector:
05 4 3 2 1
10 9 8 8 6

The tach needle receives it's signal from the PCM over the CCD bus which is pins 9 and 10 ( wht/blk & vio/brn) of that same connector

 

First of all, let me say THANK YOU GUYS SO MUCH for helping me out with this!!!

Now, about getting to those connectors on the back of the instrument cluster... How do I get to them? LOL. I mean, I tried pulling the instruments out forwards but they just disconnected from the connector. So I guess I need to get to the backside of the connector. How do I do that? Because I couldn't see a way to do it without taking off parts of the dash that run all the way down to the passenger airbag (kinda scared to mess with that). Thanks again!

 

HELP! HELP! Is the Tach wire black with a gray stripe or gray with a black stripe? I have conflicting info here.

 

PCM= Powertrain Control Module
ECM= Engine Control Module
BCM = Body Control Module
How many cotton-pickin computer do we need on ONE truck?

The PCM is on the left in the following picture, as you can see, the air filter housing is removed.

Chris

 

I found the PCM quite easily. What about the ECM though. Got a pic of it?

 

Lucky you, I actually found one. It is to the right in this picture. Notice the PS Pump cap and the fuel filter to the far right.

Oh, and you you get to working near the airbags, the recommendation is to disconnect the batteries and wait for at least 2 minutes to allow the airbag reserve power to deplete.

My Haynes manual shows the tach wire, between the PCM and the instrument panel, to be Gray with Light Blue stripe. Hope that helps.

Chris

 

Here's a nice diagram



If the pic didn't work, here's another link (click on pic to enlarge)

https://www.dieseltruckresource.com/...cat/513/page/1

ECM would be #15


phox