Electrical help

[walker111]

So I’ve recently ran out of things to tinker with on my truck.

Had the idea of hooking my aftermarket Rostra Cruise Control up to my factory switch instead of using rostra’s 250-3592 Open circuit switch.

Both switches are 4 wires. Rostra is setup this way



factory switch is setup this way




my idea was to cut the wire before the clock spring and connect the 4 wire pigtail from the Rostra cruise. Unfortunately my 2nd grade electrical skills aren’t sure if it’ll work.

Rostra is a normally open switch, I’m not sure if the factory switch is open or closed.

Speaking with Rostra, they say the red is constant power from brake switch. Brown is on/off.

there are 4 wires on the factory switch and 4 wires on the Rostra harness. According to the Rostra wiring diagram red is brake hot and brown is positive brake.



Im using the 94/95 cruise control switch with off / on / resume accel / set coast

 

[flecker]

Have you considered a mechanic?

 

[walker111]

For what? Most mechanics are parts replacers. There are a plethora of folks on the forums who are great with outside the box electrics.

My cruise control works fine as the truck sits right now. I’m only thinking outside the box to see if it can work with the stock dodge switch. What are forums for?

You seem to be at your “wits end” so go take your truck to a mechanic. Mine works and functions great.

 

[RamDiver]

Why would you suspect the factory switches are anything but normally open?

The vehicle speed control drawing posted clearly shows normally open (NO) switches, AFAIC.

You could always locate the 4-pin connector, disconnect it and test the switches with an ohm meter.

Do you own or have access to a digital multi-meter or VTVM?

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[walker111]

I got some bad advice. The factory switch is normally open.

Yes, I have a multimeter.

The current Rostra switch funtions

Red wire is constant power
Brown wire gets power when cruise is turned on
Green and yellow get momentary power when pressing set/resume.

 

[RamDiver]

I'm just curious, does this Rostra Cruise control have better features than the stock unit or is the stock unit not working?

On another note, does the OEM cruise appear to use all the same signaling voltages?

Pardon me if you've already stated this above, I'm just in from lawn cutting.
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[walker111]

I'm just curious, does this Rostra Cruise control have better features than the stock unit or is the stock unit not working?

On another note, does the OEM cruise appear to use all the same signaling voltages?

Pardon me if you've already stated this above, I'm just in from lawn cutting.
.

My factory cruise was 6 months of a troubleshooting headache. Could never get it to work. The Rostra functions the same, but no pcm and all new wires/grounds.

In terms of signaling voltages, I’m not sure. I’m not great with reading schematics.

 

[RamDiver]

My factory cruise was 6 months of a troubleshooting headache. Could never get it to work. The Rostra functions the same, but no pcm and all new wires/grounds.

In terms of signaling voltages, I’m not sure. I’m not great with reading schematics.

Yes, the PCM or ECM aspect can be a big PITA.

Did you obtain assistance here at Ram Forum while troubleshooting your factory cruise?

I'd hate to abandon any OEM systems and replace them with aftermarket but if you've already played that game, that's your call.

So, just for clarification, your aftermarket cruise works great but you would prefer to use the steering wheel controls from the OEM cruise to control it?

Could you please post the make & model # of the aftermarket cruise and include the associated url?

I'm looking for technical specs and whatever they're offering for schematics.

Also, a link to the full schematic of the factory cruise?

I'd like to see more of the factory cruise schematic posted above. TIA

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[walker111]

Thank you for your help/interest.

Rostra 250-1223

Universal add-on electronic cruise control system by Rostra

A universal electronic cruise control system from Rostra allows you to add cruise control functionality to almost any vehicle with a mechanical throttle control linkage on its carburetor or throttle body.

www.rostra.com

Instruction manual

https://www.rostra.com/manuals/250-1223Form4565G.pdf

 

[RamDiver]

That looks great and you're most welcome.

There's a good chance that we can intercept the steering wheel switches without throwing any codes because all the contacts are normally open (NO).

Have you been able to locate connector C211 on the output of the OEM vehicle speed control switch?

I would start by disconnecting that connector and using the truck to confirm it won't throw any codes.


Update;

I've used the following site for ages to identify and locate Mopar connectors. Unfortunately, I'm not able to connect to any of their sites at the moment. I'm able to successfully ping the home page, so, it still exists.

See if you can connect, enter your truck details, search speed control switch, and it will show you exactly what the connector looks like.

Mopar Connection Repair Kit

connectors.dcctools.com

Update #2;

I wanted to confirm that you have read this detail from the Rostra site;



.

 

[walker111]

That looks great and you're most welcome.

There's a good chance that we can intercept the steering wheel switches without throwing any codes because all the contacts are normally open (NO).

Have you been able to locate connector C211 on the output of the OEM vehicle speed control switch?

I would start by disconnecting that connector and using the truck to confirm it won't throw any codes.


Update;

I've used the following site for ages to identify and locate Mopar connectors. Unfortunately, I'm not able to connect to any of their sites at the moment. I'm able to successfully ping the home page, so, it still exists.

See if you can connect, enter your truck details, search speed control switch, and it will show you exactly what the connector looks like.

Mopar Connection Repair Kit

connectors.dcctools.com

Update #2;

I wanted to confirm that you have read this detail from the Rostra site;

View attachment 528285

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Yes, sir. I’ve found that plug right under the lower steering column cover. 5 wires, one being the horn. Disconnected it only affects the horn. No other ill effects.


Yes, I’m aware Rostra doesnt want me to stray away from how there system was designed.

 

[walker111]

Screwing around with the voltmeter, I believe the set/coast button has power until you press it, the resume accel is opposite.

On the Rostra switch/wiring, they both have no power until you press them.

I’m not sure if it’s even possible to reverse that set/coast on the factory switch. This idea might be a no-go.

 

[RamDiver]

Yes, sir. I’ve found that plug right under the lower steering column cover. 5 wires, one being the horn. Disconnected it only affects the horn. No other ill effects.


Yes, I’m aware Rostra doesnt want me to stray away from how there system was designed.

I trust that you attempted to start the OEM cruise after you had disconnected C211, just to verify, yes?

Were you able to connect to the Mopar repair kit link I posted previously? It's still not connecting for me.

I was thinking the best solution would be to buy the connector that is on the speed controller side, extract the horn wire from the OEM C211 and install it in the new connector with the Rostra CC.

Otherwise, you will be required to chop up the wiring, removing the option for a tidy rollback.
That is your decision though. Inline splices can be messy and unreliable, at times.

.

 

[RamDiver]

Screwing around with the voltmeter, I believe the set/coast button has power until you press it, the resume accel is opposite.

On the Rostra switch/wiring, they both have no power until you press them.

I’m not sure if it’s even possible to reverse that set/coast on the factory switch. This idea might be a no-go.

If the schematic drawing posted is accurate, both switches are NO. Both pins 2 & 4, should have no voltage until the switch is pressed. I wonder if that was the problem with the OEM CC, that the set/coast button is defective and always has 12V instead of NO?




.

 

[walker111]

If the schematic drawing posted is accurate, both switches are NO. Both pins 2 & 4, should have no voltage until the switch is pressed. I wonder if that was the problem with the OEM CC, that the set/coast button is defective and always has 12V instead of NO?


View attachment 528303

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So I have the 94 FSM and the 94 diesel supplement. This is the diagram in the diesel supplement.


If I’m not mistaken, the diesel supplement shows set with power?

 

[walker111]

I trust that you attempted to start the OEM cruise after you had disconnected C211, just to verify, yes?

Were you able to connect to the Mopar repair kit link I posted previously? It's still not connecting for me.

I was thinking the best solution would be to buy the connector that is on the speed controller side, extract the horn wire from the OEM C211 and install it in the new connector with the Rostra CC.

Otherwise, you will be required to chop up the wiring, removing the option for a tidy rollback.
That is your decision though. Inline splices can be messy and unreliable, at times.

.

All of the factory cruise control stuff is gone (in my garage) minus the switch. I have extra switch and both side connectors.

I like that idea other than the set power problem.

 

[walker111]

Also, you keep typing NO, I assume this is no power, but what does the O stand for?

 

[RamDiver]

Also, you keep typing NO, I assume this is no power, but what does the O stand for?

I made the reference earlier, with the definition and just got lazy. NO is normally open.

The standard nomenclature for switches are normally open (NO) or normally closed (NC).

The diesel supplement certainly adds pertinent details. Too bad they had to add that NC contact on the set button.

This will add more complication but still possible. You would be required to add a relay in order to invert the set button state.

Is the brown/red (BR/RD) wire normally at 12V when you measure with the DMM?

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[walker111]

Normally open, NO
Normally closed, NC
Got it! Thanks

the br/red is disconnected on the column side. I’m not sure what the pcm usually gives it.

 

[RamDiver]

I apologize for my slow response time, I'm trying to find a method to make this information more presentable and easier to read.

I've found the type of relay but can't apply tidy labels. LOL

It looks like this one, a SPDT (single pole, double throw).



I do have some mild concerns about the Rostra CC, not being happy but it shouldn't fry. You must understand that if you decide to make these modifications, I'm providing no guarantee your CC will function correctly or not fry.


PS: this is a stock generic pic that already had these labels. I'm trying to make new and presentable labels that are specific to your project.

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