babyfood1217

the truck - '88 4runner 22-re

These issues pertain to the electrical circuits for the oil pressure and the engine temp. SR5 cluster with the appropriate senders installed. I was getting no reading from the oil gauge in the cluster, and the wiring installed to both the oil sender as well as the temp sender was not part of the factory harness (ie: it was random wire that the PO used to jumper the senders to the gauges.) Turns out these extra wires were put in because there are shorts in the harness wires. I figured this out by finding all the original wiring that would attach to the senders. Wire for the oil sender was stripped of its' connection and coiled up behind some other stuff. Wire for the temp sender still had its' connector but was corroded and stuff under some of the injectors. Cleaning those wires up, I reattached them to the senders, and after confirming the wires into the gauges were good, I fired the truck up and got absolutely no readings.

I reverted back to the "jumper" wires the PO put in, and the temp gauge worked again. Oil was still a no go, so I hooked a crappy SunPro gauge up to the wiring, and it immediately spikedActually, it didn't fully spike. It went up to 100, and I'm pretty sure that's too much, though the engine is fresh and tightly buttoned up.. This aftermarket gauge is brand new, so I'm pretty sure I've got a bad sender.

So I know I need a new sender, but I very much want to keep the stock cluster. My research here also leads to the notion that the stock gauges are pretty much worthless, but I want to get the wiring back in order so the ECM isn't getting bad signals/lack of signal.

I'm going to try to, for the time being, just run an autometer/sunpro type aftermarket electrical oil pressure gauge so I at least have something.

My problem/concern is tracking down the short in the wires. I understand how to use a multimeter, and I understand how to systematically work through a wire length to determine where a break/short may exist, but how difficult will it be to replace these wires? I feel like I'm going to have to gut the entire engine bay to access the entire harness. Is it really as scary as it seems? Will replacing those wires be as much of a hassle as I'm anticipating it to be, or am I just freaking out.

Ugh.

Electrically Frustrated!

-C

myyota

The hardest parts is finding the break and unwraping the wiring harness, more time consuming than anything else. Have you tried running a new wire from the temp gauge plug directly to the tem sensor to see if it works ?. Also check all of the grounds on the gauge cluster, tighten all of the nuts and screws on the back of the gauge cluster.

babyfood1217

I have an auxiliary wire connecting both the oil sender and temp sender up into the gauge cluster now. The PO put them in (I can only assume he found there to be wiring issues and figured it would be an easier and quicker fix to run jumper wires rather than track down the actual issue.) It works, sort of. Temp gauge (in the cluster) is working fine with this method. The oil pressure gauge is still not even working a tick, but when I hook an aftermarket to the oil pressure sender via jumper wires, the gauge runs all the way up to 100 (not a complete spike like when you ground a circuit) but it seems just a tad high, right? A mechanical oil pressure tester yields good results, but I really want to get the wiring back to a slightly cleaner, tidier position. It's a mess of wires all across the engine bay right now, and I need it to be not so, especially as I begin to work through the truck and tackle other issues.

babyfood1217

And though this is something I will do after I get the factory wiring figured out, I would like to find a more reliable gauge alternative. Would a Sunpro or Autometer type gauge really be superior to the factory gauge? I seems a lot of people run the T fitting to keep stock sender (keeping the ECM happy) but running a mechanical gauge as well. Why the choice of the mechanical vs. the electrical?

babyfood1217

Update: I just parked the truck after driving it for a bit with a new sender in. Jumper wires from new sender to aftermarket gauge reads everywhere between 25 and 70/75 depending on temp., rpm, etc. Awesome!

But, I'm curious what kinds of codes/ECM dialogue this is creating? The mechanic who did recent engine work for me said the only code he could not get to go away was code 51, but shouldn't there be a code thrown by not having the oil pressure signal running??