Motor swapped 1980 450SL wiring questions

[Crclerx]

Okay, so before I’m publicly executed for swapping a Toyota 1JZ into my 1980 450SL, hear me out:

The old motor was impossible to work on. Parts were expensive, every day it left me stranded for no reason at all and then would start up again, and no one else wanted to work on it. Of course a cheap and reliable swap made sense for me and it’s not butchered to where you can tell. It’s clean and nice. Reliable just how I wanted it.

But I have 2 questions now:

1. One day i came on and then off and then stayed on for good. With the head lamps on (or in parking lamp position), the left side turn signal stays solid on and the right side is fine. I mean ON like front, rear, and cluster indicator solid on and will not blink. Works fine with the head lamps off. I’ve tried to unplug the multifunction switch and the hazard switch to see if it makes a difference but to no welcomed change. I cannot for the life of me find proper wiring diagrams on line and have no idea where to begin my chase on this. Any input would be appreciated. As I said, one day it just happened and stayed on forever. Right side is okay.

2. With the motor swapped, I’d like to keep the cluster gauges. My most important gauge to keep is my water temp. I figured I could tap in a 450sl water temp sensor into the Toyota motor and wire it back to the cluster but I have no idea which wires at the cluster will be correct for this.. again, cannot find proper wiring diagrams.

Any help would be appreciated and backlash from the purists will be heard but ignored. I hear enough of it from pretentious old Orange County guys at cars and coffee. Thanks guys

[Frank Reiner]

Originally Posted by Crclerx

Okay, so before I’m publicly executed for swapping a Toyota 1JZ into my 1980 450SL, hear me out:

But I have 2 questions now:

1. One day i came on and then off and then stayed on for good. With the head lamps on (or in parking lamp position), the left side turn signal stays solid on and the right side is fine. I mean ON like front, rear, and cluster indicator solid on and will not blink. Works fine with the head lamps off. I’ve tried to unplug the multifunction switch and the hazard switch to see if it makes a difference but to no welcomed change. I cannot for the life of me find proper wiring diagrams on line and have no idea where to begin my chase on this. Any input would be appreciated. As I said, one day it just happened and stayed on forever. Right side is okay.

2. With the motor swapped, I’d like to keep the cluster gauges. My most important gauge to keep is my water temp. I figured I could tap in a 450sl water temp sensor into the Toyota motor and wire it back to the cluster but I have no idea which wires at the cluster will be correct for this.. again, cannot find proper wiring diagrams.

Any help would be appreciated and backlash from the purists will be heard but ignored. I hear enough of it from pretentious old Orange County guys at cars and coffee. Thanks guys

Cool!! There is no reason for anybody to get their panties in a twist.

"One day i came on and then off and then stayed on for good."
There seem to be a couple of words missing here. But the problem that you describe is likely caused by a grounding fault. Remove & clean all the ground connections (brown wires) in the headlight area.

Do you still have all of the original MB wire harness? If so, take the temp sender from the MB engine, and match the harness-to-sender connection.