Cruise Control / Brake Light Switch Part Number

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Fresh Air Inspector

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Hello All,

I've managed to gather together most of the bits for a cruise control set-up. However, the brake light switch appears to be a bit of a challenge. According to my factory service manual it has 6 terminals which strikes me as strange. The only part numbers I have been able to find are 'SLS-99' which appears to be an aftermarket item and '2947798' which seems to be a MOPAR part number. The ones available on eBay are VERY expensive and are 4 terminal switches - which makes sense; two for the brake lights and two for the cruise.

Hopefully someone out there can shed some light on the subject.
 
Hello Volare 1977,

Appreciate the quick response. Unfortunately the link you sent me is for a different part. The eBay item is for the front wheel drive platforms from Chrysler. My car is a rear wheel drive M body '88 Plymouth Caravelle (Gran Fury in the US).
 
4221979 - Stoplight switch w/o Cruise

4221980 - Stoplight switch with cruise

I don't know where you could find the 4221980. Dealer search, Internet search. Most likely the boneyard.
 
Hello AHBguru,

Thanks for the part numbers - always helpful.

Hello volare 1977,

Thanks for the eBay link - I've purchased the switch, just waiting for it to arrive. :-) Interesting that the 'correct' (??) aftermarket part number is SLS-135.
 
I used a DPDT industrial control relay with a 12VDC coil in a similar application. I wired the coil of the relay in parallel with the brake lights.

The PCM from the magnum engine needs a "brake on" signal to properly operate the torque converter lock up. One pole completes the circuit to ground to the PCM for the TCC. I used the other pole for the brakes on signal to the cruise control.

I did this because the Aspen brake switch, no cruise control, is a single pole and I needed 2 more poles for the PCM. The donor truck used a 3 pole brake switch.
 
Hello Magnum Aspen,

Interesting solution to your set-up. I assume you installed an A518 (46RE), transmission with overdrive and lock-up TC. I'm going the same route but using the '95 and earlier A518 (46RH), that uses hydraulics (no electronics :-) for O/D and TCC. The company below has a nice solution for the 46RH version.

Lock Up and Overdrive Kit, Dodge 727 to 518 Conversion

For some strange reason on my '88 Plymouth, Chrysler uses a 2 pole brake light switch in 'non-cruise' vehicles and a 6 pole brake light / cruise switch. A separate 2 pole switch for the brake lights and a 4 pole for the cruise. I assume other years had the same set-up.

Thanks for the feedback.
 
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