Thread: Adding diagnostics to an older vehicle

Yep - transplant all the sensors & smarts off a newer Caddy with diagnostics...

Or write your own....

Has anyone done a sensor transplant that you know of? Any links would be helpful. (My Google-fu is pretty good, but the best forums rarely show up.)

No - people I know of found it was cheaper buying a newer vehicle....
Because engines & setups change, there is rarely any 1:1 exchange.

Paraphrasing, it would be easier (and probably cheaper) to by a new vehicle and put your stuff in it, then modify for the bits that are different.


There are people that have implemented partial solutions, but even if links existed, they'd be largely useless - I'd be better linking some uPC Beginners Guide and ELM-chip datasheets etc.


My original reply was trying to convey a "no" answer by highlighting the reality.

there is nothing digital/electronic on that car its all mechanical, maybe you could replace coolant sensor with temp probe and use fusion brain, fuel level sensor and you might get rpm i really can't see getting anything else from car. these days mechanical gauges are really cheap compared to 20 years ago might be your cheapest solution SNO

To integrate OBD2 into your system I didn't see the possibility, but if you want to monitor "something" it can be done by install sensor for each purpose and make some small piece of work on microcontroller. for example install new air flow and monitor it, O2 sensor, TPS (if you could find the right size) etc

Thanks, everyone.

So, what I'm reading is stealing an OBD2 from an existing car isn't at all worth it (which makes sense... I couldn't tune my car with it, either), but I CAN add sensors and get the diagnostics readout.

@SNO, I've thought about mechanical gauges, and I'll use as many as I can in the original dash, but the main reason I wanted the obd2 was just for the monitoring and trending.

@Saran_yim, if I go the route you're speaking of, do you know of any guides or existing pieces of hardware or software that could help me out?

Really, diagnostics on this vehicle are limited to lifting the hood and looking listening.
This is a really cool car, I would just love it the way it is.

Without great difficultly you should be able to monitor; not diagnose, monitor oil pressure & temp, water temp, voltage and or amperage, vaccum, engine running hours, fuel level, RPM, washer fluid level, int & ext. ambient temp, tire pressures, and maybe a bulb monitor for burned out lights.
Beyond that, adding things like MAF & MAP sensors etc, really don't make sense on an old carb engine. You certainly could add an alarm remote start and maybe tie into that as well.
Everything I have listed above would keep you busy for a while and would actually output useful data to running and maintaining that classic you are so lucky to have your hands on!
Now how about a couple of pics for us??

@PhilG, thanks for the list!

I need to upload a ton of pictures I have on my computer (most of them are documenting cancer spots and other problem areas, but I'm sure there are some great pictures of it in my library), but there are two pics floating around online.



It's in my garage now, not this storage shed, and it doesn't have as much crap inside it, or the mattresses on top of it). I am happy to say it's only been out in one winter since I bought it ten years ago, but 30 years of Utah winters (and the subsequent salted roads) has taken it's toll.



When I first bought the car, I had to change the starter, so while it was sitting in the garage I snapped this picture with the B&W film-based camera my little brother had from school. Now that I post that, I remember he took a couple sweet pictures of my car as well... I'll see if I can get him to scan them.

Ha ha - my car is one year older!

But is has the "essential" improvements - like halogen headlights (relay operated of course!), modern HU & surround speakers, and a voltmeter (the only digital-display sensor).

Key performance and reliability upgrades include a modern (late 1980s) alternator with inbuilt regulator (forget external regulators!); modern power-source distribution (plastic fuselinks near the battery); 5-speed box; LSD and a newer 1969 pushrod engine.
And an electronic (reluctor) distributor & igcoil from a later ~1985 variant that is so good, I never bothered fitting sequential CDI. With its ~1985 reduction starter motor, she cold starts with a 5V battery. (Yes - it is a 12V system.)

Though I also fitted a later 1985 instrument cluster and gauges, that was mainly for its metric speedo & now I'd recommend a GPS instead. However, the stable fuel gauge and its low fuel warning light is a godsend, and it has more & better idiot lights.

She still runs a carby and a mechanical fuel pump (I use to hate those!) but an electric pump awaits in situ as a backup.


The chance of her being stopped by external alarms and communication systems, atmospheric nukes & satellites - roughly zilch. (I carry spare points dizzy etc.)

The chance of bypassing some electrical problem - big! (But I try for redundant design anyhow...)


The chance of me getting a modern security integrated vehicle - AFAIK nil (too risky!).
The chance of transplanting more modern devices - big if desired.

The chance of a typical OBD system - no; why?
But other monitoring with redundancy & failsafe alarm philosophy (eg normally open oil pressure & normally closed engine fan switches thru inverting relays or circuits) - oh YES! Headlight reminders, distributed temp sensors, whatever.