SR5 Cluster swap fuel gauge help (3 Viewers)

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ariff

ariff

Joined
Dec 29, 2016
Threads
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432
Location
Lawrence KS
Hello Everyone,
I am hoping some of you might be able to help me out with an SR5 cluster swap I have done in my 87 pickup (22R) Everything that I have read says this is an easy swap as long as you change out the oil sending unit everything should just work. I have done all that and for the life of me I am not able to get the fuel gauge to work. I swapped in my old non SR5 cluster and the fuel gauge works so I don't believe it is a sending unit\wiring issue. I have removed the SR5 cluster and checked all traces and everything appears to be ok. There are two diodes on the back of the cluster I tested those and they appear to be ok as well. I removed the fuel gauge\amp meter unit and inspected everything and it looks ok. Just three resistors. I tightened up all the screws\posts on the back of the fuel gauge also. Still no dice. When it is connected to the truck and I turn the key on I notice the fuel gauge will move slightly down. If I manually move the needle up and turn on the ignition it will pull the needle down. I am beginning to think maybe the gauge is actually bad. Does anyone know how to properly bench test the gauge to see if it is working? Here are pics of the SR5 cluster and my OG cluster. It is driving me crazy lol.. I have been told it should not require a specific SR5 Sending unit to work. Any help would be greatly appreciated. Thanks!
Original Cluster
20250527_230100.jpg


Original Cluster Back
20250527_230022.jpg


SR5 Cluster
20250527_224918.jpg


SR5 Cluster Back
20250527_230043.jpg


Fuel Gauge connections SR5
20250527_221500.jpg
 
Have you traced the fuel gauge wire on the PCB to where the connector goes in to make sure that your fuel gauge wire on the harness side is in the correct spot? I know on my SR5 swap I had to trace a few of them as the circuit was different than what the wiring diagram showed.
 
I have a feeling that's what's going on. If I apply 10v to the red + and black - in this pic the gauge moved up. If I reverse them the needle moves down. So seems like the gauge works
20250528_152803-EDIT-EDIT.jpg

If I trace those wires back I get gnd on the positive and 12v on the neg. So I switched the Red\Yellow pin C2 and Yellow Red Pin C5 and I got the same results.
wiring.jpg

So that's a bit confusing to me I then found the factory pinouts and I am having trouble figuring them out. I see on the cluster with Tach C6, C-5-1 (not sure what that means) Without Tach I see C-5-2 (Not sure what this means) and C-6. Then it looks like the fuel gauge and temp gauge on the tach cluster share C-4-1 and C-5-2. I am wondering if I should switch pins 1 and 2 red\green and red\yellow. I am just a little nervous I may damage something. Hopefully someone can help me out. Here is a pic of the wiring diagrams..
pinout.png
 
you need to have key on from pin 11. that runs through the gauge and OUT pin 5 to the sender.

both clusters appear to be pinned the same. however my ewd (86) shows pin 11 as yellow. may or may not be relevant but this is what you should be seeing
 
here. should also show voltage on your red. toggling resisted ground through the yellow wire in #5 should change the gauge position

Screenshot_20250528-181149_Chrome~2.jpg


Screenshot_20250528-181402_Drive.jpg
 
gnob said:
you need to have key on from pin 11. that runs through the gauge and OUT pin 5 to the sender.

both clusters appear to be pinned the same. however my ewd (86) shows pin 11 as yellow. may or may not be relevant but this is what you should be seeing
Click to expand...
Thanks for the reply and bear with me as I try to understand this LOL.. I did some more testing and Pin 2 and 11 on connector C show ground with ignition off then 12v with ignition on. The red screw on the fuel gauge in my pic is constant cround all the time. The top screw you circled is gnd with the ignition off and 12v when ignition is on. The Screw labeled - is gnd all time. Could you elaborate more on "toggling resisted ground through the yellow wire in #5 should change the gauge position" as it is always showing ground. How would I accomplish this? Thanks again!
 
your red screw goes to pin 5.
power comes into the gauge from pin 11. exits the gauge from your red to pin 5 then goes to the tank sender.
the gauge moves based on that resistance value. the values should be shown in your fsm.

if you don't have some kind of voltage at #5 with the key on, you have a gauge problem. it should not be grounded.
 
gnob said:
your red screw goes to pin 5.
power comes into the gauge from pin 11. exits the gauge from your red to pin 5 then goes to the tank sender.
the gauge moves based on that resistance value. the values should be shown in your fsm.

if you don't have some kind of voltage at #5 with the key on, you have a gauge problem. it should not be grounded.
Click to expand...
Yup I double checked I never get voltage on pin 5. Checked with a meter and test light. Crap sounds like the gauge is bad. Wonder where I can source one of those? I have one from my 93 Land Cruiser and it looks pretty much the same. I doubt it is though. Could not find any part numbers on it..
 
I also checked the three resistors on the fuel gauge\voltage meter circuit board and they were all within tolerance. I went ahead and re-flowed solder on all the solder connections and that did not help any.
 
I think maybe you are correct and I have a bad gauge. I found this in the FSM:
fsm check.png


My reading across the IG-E terminals only shows 40 ohms. The other two readings were 96 and 130 so a bit out of tolerance. I am going to source a new gauge and try swapping it out.
 
The Plot thickens LOL I think I figured out what was wrong with mine. The previous owner must have removed the gauge and flipped it around and put it in backwards. I noticed this from looking at some pics of other gauges online and noticed that the fuel gauge looked like it was mounted on the circuit board backward one of the mounting legs is triangular in shape and it was not oriented properly as compared to pics online I found. I removed it and flipped it around. Since I noticed the needle would move down when I turned on the truck I thought hummmm maybe the po did something. I installed it in the truck and Bam the needle moved up as it should. I took it for a drive and it bounces all over like crazy. This must be why the po did this. My old non sr5 cluster works just fine so I am assuming it's not a sender unit issue and a gauge issue. Anyhow I was lucky enough to find a seller on Ebay that had a tested\working gauge for sale I purchased. I'll report back here when I install it to let everyone know if it resolved my issues. Tahnks!
 
remove each phillips head screw 1 at a time ONLY

use like 1500-2000 dry emery cloth POLISH ONLY the round copper area where the SEMS SCREW washer seats ....

use NEW screws if possible ? if not ? Polishes Bottoms of ALL the flat washers as well ..


this is a KID GLOVES polish out to BRIGHT copper once again to archive good current flow to that contact point ..

let us know if this is the smoking-unicorn gun ?


i have had to do this so many times in Toyota Life , that i now always just do them all no matter what from the get go

remember : 2025 - 1987 = 38 Full Rotations ( Years ) ...... yea ...:idea:

bright cooper work , works wonders


matt

.



oh ...........

is your fuel tank sending unit on your 87 a single / 1 wire or a double / 2 wire style type ?
.
This is a double / 2 wire type below .....fyi
.
1748607560646.png








.

​
 
Last edited:
ToyotaMatt said:
remove each phillips head screw 1 at a time ONLY

use like 1500-2000 dry emery cloth POLISH ONLY the round copper area where the SEMS SCREW washer seats ....

use NEW screws if possible ? if not ? Polishes Bottoms of ALL the flat washers as well ..


this is a KID GLOVES polish out to BRIGHT copper once again to archive good current flow to that contact point ..

let us know if this is the smoking-unicorn gun ?


i have had to do this so many times in Toyota Life , that i now always just do them all no matter what from the get go

remember : 2025 - 1987 = 38 Full Rotations ( Years ) ...... yea ...:idea:

bright cooper work , works wonders


matt

.



oh ...........

is your fuel tank sending unit on your 87 a single / 1 wire or a double / 2 wire style type ?
.
This is a double / 2 wire type below .....fyi
.
View attachment 3917807







.

​
Click to expand...
Polishing those contacts was one of the first things I did and it did not help anything. As for my fuel sending unit I am not sure, but since it was a base model truck I am assuming it will be the two wire sender. I am hoping to convert it to a three wire to get the fuel warning light to work.. I'll cross that bridge soon when I remove the bed.
 
gnob said:
make sure the cluster actually has the light, first... ask me how i know 😂
Click to expand...
LOL it does he sent me pics of it. Do you have any experience making this light work on a non SR5 truck? Looks like to me the C10 connection yellow and blue wire is what is uses.
 
as long as the wire is there its gravy.
otherwise you will need to add the wire from the cluster to the sender. but its simply just that one wire. it works like the sender. power from the key, through the light and grounds through the sending unit.
that diagram i posted above shows it
 
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