87 4runner, was sold labeled as an sr5 though it has DLX equipment all over it. And that's a story I in no way under. I just put in the sr5 cluster from my other truck and noticed that the tach will just sit dead even on 1800 rpms for a while. However, sometimes it will read correctly. Such as after I sit at idle for a long time or just at random times while driving. I am running a deep cycle marine battery, so I thought it would be the cause, checked it and I saw 12.7v with key off, 12.4v with key on for some reason, and 14.0 with the truck on. I got out today and checked it while the tach was working, and got 13.76 volts. Also, when the key is put the on position, the tach jumps straight up to that 1800 rpm mark, though when the tach is working, it reads 0 like it should, seeing as the coil is telling it 0 rpm. Now my questions, and there are two. Many. Too many. Get it? hahaha, anyway.

Is there a voltage regulator on the dash somewhere I can check? Will a marine (deep cycle) battery not run a charged system, or alternator system? Could grounds be the culprit?

Okay, also, my oil sending unit only reads in an area of about an inch. From a little below the bottom acceptable line to a little above it. Is there a relative torque spec for the sending unit to engine block connection? Shouldn't the oil pressure shoot up if I open the throttle and build up 5000 rpms?

Coolant temp sensor. I've heard and seen all sorts of problems with these things. Mine is this. Key to on position, truck off, it goes to the middle. It pretty much stays there permanently even after the truck warms up too. Is this normal? I mean, maybe my truck just so happens to warm up to the middle of the gauge, but on the old cluster, this truck ran cold. Only a small amount above the bottom normal line, just like I like.

If you could answer anything, let me know. Thanks in advance for any input.

 

Continuity readings. I'm getting good grounds to the truck, radio works like it should and so do most other lights. The lights for the AC controls don't work, except for the AC button. However, on the back of the cluster, just between itself, it has continuity, but it isn't as good as I'd like really. Worst spot I could find on the old cluster only gave resistance at .11 for the 20k setting on my multimeter. The sr5 cluster sees that as about its best numbers. Can't help but wonder if maybe the old style circuit pad is worn out that makes up the cluster. Anyone have any input into this?

 

Firstly, I wouldn't worry about your battery voltage and charge circuit...from the numbers you posted everything looks fine!
What truck did the SR5 cluster come out of? If it was an 88 or 89(4Runner) you may have a V6 cluster and that won't work properly with the 22-re. Search for the "10Kohm resistor mod" and the "ten turn potentiometer mod" to correct this problem. If you are not sure what the tach is, remove the front of the combination meter there should be writing on the top edge to the tach telling you if it is a 4 or 6 cylinder.
If the cluster you added is not from an 87 or has a different transmission (auto vs. manual) then you may have to verify the pin configurations of the three connectors that plug into it. These swaps are not always plug and play, you will need access to wiring diagrams to verify the proper pin configuration. For example the cluster out of an auto (86 4Runner or Pickup & 89 4Runner) has different pin configurations for the fuel gauge sender, the fuel and temp gauge ground and the tach signal input from the igniter.
You may have a bad ground on the combination meter causing all of your gauge problems; on the 86 the combination meter ground is under the left kick panel, on an 89 it is on the dash support behind the cluster. I suspect that your 87 is the same as the 86.

 

Thanks for the reply Hadmatt! Actually, the 87 has a ground just below the bottom of the A-pillar just like the 89 does. That ground is getting good continuity to both body and battery, I checked both to be sure. However, when I jump the positive of the tach to ground, I get a resistance reading of ~.750 with my DVOM on the 20k setting. When I cross IGN to the Japanese symbols I get nothing, indicating a lack of ground, but I know that other parts of this cluster are grounding fine, such as the fuel gauge, which should also malfunction with a lack of ground, as the tach and fuel gauge use a parallel ground. At this point, seeing how much resistance is in my cluster, I'd like someone to tell me if that is normal, or if I can call the sr5 cluster I have defective. I'm a nood so if someone could help, yeah......... That'd be greeeeeeaaaaaaaaaaaaat...

 

Oh yeah, forgot to mention, the cluster is from another 87 4runner 22R-E with a manual transmission, so no adjustments should be needed.

 

Are you talking about the signal wire from the igniter or did you measure to ground where this wire connects to the tach?
Either way you are going to read a resistance, be it tach or igniter.

 

Signal wire from igniter. I believe it's labeled p on the back of the cluster where I'm reading it from. But I even get bad readings from ign to ground or the Japanese symbols. Something should have a clear ground I would have thought.

 

are the harness connectors plugged into the cluster when you are trying to take ground measurements? Most ground points on the cluster aren't grounded until the harness is plugged into the back of the cluster. There are generally one or two ground wires in the harness that actually connect the printed circuit grounds to system ground, that's why the harness has to be plugged in when attempting ground measurements.

 

Yes they are. I've checked the harness grounds and they're good as well.

 

Silly question...I was going to start a thread on erractic tach behavior on my 87 4Runner and just saw this in the "new posts" section.....

I've been having idle issues and replaced my IACV recently, then set idle at 850 warm - everything seems fine. THEN, couple days ago, my tach starts reading like 200-300 RPMs when warm at idle. BUT, the motor sounds like it's idling just fine. I adjusted the idle screw up and now it's too high (though it READS 850).

Any idea what could cause this all of a sudden?

And, how are you guys testing - is that in the FSM - what section?

 

Hello 87blackbeauty &Hadmatt54 I was wondering if you can help me verify some voltages i see you are talking about the IGN signal at the Igniter and coil is that signal suppose to be around 5 volts and the NE signal voltage around battery voltage ?
Do you understand how the ignition system works the IGN,NE,IGF ? thankyou

 

Really late reply, but when looking at your cluster from the back, there are 3 screws in the back of the tach. Left one is the feed from your igniter. Middle is switched power. Right is ground. If you're having issues, I'd suggest you test the cluster in a known good vehicle wiring harness to make sure it's 100%. I still need to do this with mine. I just don't have a known good test vehicle. Or a known good sr5 cluster to test in my truck. Two way dilemma. Also, my problems still persist. I'm tempted to just get my trusted mechanic to fix it for me.

 

Any ASE certs out there? I got a couple pictures for you to look at.

This suddenly started happening. (The radio) And it was always changing but never made any words or anything.



But I noticed that at the same time that this started happenning, this happened too.



That's my tach working. The key is in the on position, and the truck is off. Dead on 0. And I also know it was working with the truck on because I just suddenly noticed it screwing up while I was driving. So I turned off the truck, all the way. Then put the key back to the on position. Guages including tach still working great, but the radio was normal again. I didn't care, I was like COOL! and proceeded to pull off the shroud to plug in my clutch start cancel button and screw it back in and as I moved the shroud, the tach jumped back to 1800 and quit again. Now surely this story can help someone with more knowledge than me figure it out. I mean, that HAD to mean SOMETHING, right?