ECM delete to do list questions

[ofelas]

Hi, on a 91.5 auto 4x4, if I want to do an ECM delete -

1/ Grid heaters - momentary on pushbutton switch - blue wires from heater relays grounded via the switch

2/ TPS - shouldn't make a difference as all it does it set the 3rd to 4th shift point

3/ OD - red wire off the OD solenoid grounded through a 2-pin toggle switch

4/ Speedo - blue wire off the VSS grounded to chassis

5/ Rear ABS - not affected if I unplug the module

6/ Charging - not affected, as 91.5 is regulated externally

7/ AC & cruise - don't have these on my truck

8/ KSB - not sure what the will affect

9/ Fuel heater & water in sensor - use the Cummins delete nipple and go with an integral drain Fleetguard FS1221 or similar)

10/ The FSO shouldn't be affected

The coolant temp switch, trans temp switch and air temp switch can be left connected as they are now redundant

With the harness unplugged at the ECM, the truck starts, runs & turns off just fine, except that the grid heaters and OD don't get a closed ground circuit.

Anything else Im missing?

 

[the2finger]

Gee when the North Koreans nuke us you'll still be running

 

[DVolk]

really only thing you need is a hot wire to the pump to make it run

 

[ofelas]

About the OD - instead of an on-off 2 pin toggle, how can I use my factory OD switch to complete/interrupt the ground circuit, and can I have it light up when OD off like the factory does it?

And on the pushbutton switch to the grid heaters - makes sense to ground switch the blue wires, do they get grounded by the ECM signal from the input wires orange/black & yellow/black ? If so, couldn't I just put a switch in-between the yellow/black & orange/black wires & ground?

Is there a difference grounding the blue wires vs the orange/black + yellow/black?

Thx

 

[cerberusiam]

The OD off switch is a momentary switch that activates a digital switch in the SBEC. You need the digital to back up the momentary. An on\off type switch will be needed if you delete the controller.

Pretty sure you just need a switch on the sense wire for the heater relays. The relays should be powered and the SBEC just grounds the circuit to activate it.

 

[ofelas]

Ok - so if I understand right - if I keep the ECM, then the momentary switch works in tandem with the factory button, I just splice a lead into the OR/WH trigger wire & ground the other lead.
If I delete the ECM, then the momentary won't work - I need a constant on-off.

On the heater relays - I thought of having a momentary pushbutton hook into the BK/OR and BK/YL ground signal wires coming from ECM pinouts 15 & 16.
So my pushbutton would pretend to be the ECM, except it would be thumb operated, not triggered by the intake air temp sensor.
Would that work ?

Thx

The OD off switch is a momentary switch that activates a digital switch in the SBEC. You need the digital to back up the momentary. An on\off type switch will be needed if you delete the controller.

Pretty sure you just need a switch on the sense wire for the heater relays. The relays should be powered and the SBEC just grounds the circuit to activate it.

 

[RWherley]

Just wondering why you want to go through all this work to get rid of ECM?

 

[ofelas]

Fried.
No replacement available.

Just wondering why you want to go through all this work to get rid of ECM?

 

[cerberusiam]

Ok - so if I understand right - if I keep the ECM, then the momentary switch works in tandem with the factory button, I just splice a lead into the OR/WH trigger wire & ground the other lead.
If I delete the ECM, then the momentary won't work - I need a constant on-off.

On the heater relays - I thought of having a momentary pushbutton hook into the BK/OR and BK/YL ground signal wires coming from ECM pinouts 15 & 16.
So my pushbutton would pretend to be the ECM, except it would be thumb operated, not triggered by the intake air temp sensor.
Would that work ?

Thx

Yes, I don't have one handy to look at the wires for the heater but it sounds plausible. Without the ECU you will need a switch for OD of some kind. The OD off becomes integrated with that switch.

 

[Waynes]

Ofelas,

I lost my ECM about a year and a half ago on my 91.5 auto D250. I used a momentary toggle to the grid relays, and a lit toggle taped to the gearshift handle for overdrive. Cruise control was dead, and no water in fuel light. This was all fine except I really wanted cruise control back. I bought a used '92 ECM and it got everything working except the overdrive shift. I cannot be sure if the lack of overdrive shifting is due to the ECM or due to the TPS or something else, as I had occasional problems with it shifting before my ECM fried. Your list looks good, don't know about using the ECM pinouts but I expect that could be made to work too.

Wayne

 

[ofelas]

Hi Wayne,

Did the 92 PCM work even with the 91.5 external voltage regulator?

Thx

 

[DVolk]

other than the grid heater operation plug a mini van one in and go

 

[ofelas]

Will this work on an externally regulated 91.5 ?
OD, speedo, AC ?
Details of the minivan model ?

 

[DVolk]

Get one from the same year if it has the over drive transmission , it should work for a mnual , any year should work , dodge didnt re invent the wheel on every application they just pull parts off the shelf the plugs are all the same from what ive seen . you copuld probally even have one re programed as well

 

[Waynes]

Hi Wayne,

Did the 92 PCM work even with the 91.5 external voltage regulator?

Thx

Yes, the firewall mounted voltage regulator still does the regulating. The only item I don't get with the '92 ECM in my 91.5 is the overdrive shift. The water in fuel light seems to work, voltage regulating, grid heaters and cruise control all work.

I did borrow a '94 diesel ECM to try out - it got the cruise control working, the voltage regulator still worked (worked with the fried ECM as well), but no grid heater, no overdrive. It is possible my 92 ECM would control the overdrive but the rest of the circuit has a problem - haven't really looked into it.