Gauges don't work! How do I fix them???

[Thefarmboy21]

Ok so after sitting for 10 years, I've finally got my 87 back on the road again. Sitting that long is ******* anything and mine is no different. I'm trying to just drive it around local and work all the bugs out before I decide how much I'm gonna sink into it.

The electronics do not function correctly. The gauges don't work right at all I don't think. Sometimes they don't move and sometimes they do. The temp gauge never moves up hardly at all, the tachometer takes spells wen it does or doesn't (reads 200rpm at idle when it works, is that right?) as does the speedo. When I am in reverse the speedo actually goes backwards past 0 until its hits the peg. And the oil pressure gauge always either reads nothing or very very low, But I have and aftermarket gauge that tells me it runs between 25 and 50. The voltmeter seems to actually work and read correctly but I have no idea if it is truly accurate or not. And my engine light does work because anytime the oil psi drops to zero on the factory gauge it kicks on. And the fuel gauges jumps around and reads full until it gets down to about 1/2 tank I think. BUT I havent used the rear tank yet.

SOOO.....the big question, How do I fix it??? New senders, clean senders, new gauges? I don't really care much about any of it besides the temp and speedo, but I'd like the tach to work correctly too. BTW Im pretty sure I know where I can get a cluster if I need it. Called a guy parting out a 91 350 and I'm goin to attemp to buy the rolling chassis after he gets what he wants from it. He said what's left of the cab on the frame and axles for $300 I think. BUT you can't count on this guy :/ Thanks guys, this forum has been a great help so far.

 

[riotwarrior]

I'd start by removing the cluster and once you have it out cleaning all the contacts with a eraser or very soft scotch brite pad. Nothing too abrasive, do the same to the plug on the end of the harness.

Don't know whats wrong with speedo you didn't say actually if it functioned or not, You can always draw the inner cable out then squirt in some lubriplate or speedo lube from Napa or other parts store then insert the cable back in and make sure you get it all the way in so once it's in you cannot turn it cause it's clicked into the transmissions end. to test just drive the vehicle a few feet and observe if the center drive cable moves..if so your golden!

Also all the sending units could be corroded so you may want to unplug wires clean wires and senders and reconnect, as for the tach pull the sending unit clean the end install it back in place. Once you have done all this and have results report back for update and questions if it's still not working.

JM2CW

Al

 

[icanfixall]

Well the way you describe how the gauges are working or not working kinda tells me there may be a ground issue. That or the VVR on the back of the dash is bad. The VVr is the variable voltage regulater to the instrument panel and gauges. It can make the gauges do crazy movements...

 

[redneckaggie]

if you want to keep it i would pul the cluster and chunk it an put all autometer guages back in

 

[Thefarmboy21]

The speedo turns backwards in reverse. Most of the time it works (I don't know about accuracy) but sometimes it doesn't.

I'll pull it and clean it all but how do I clean/replace the tach and temp sensors?

 

[riotwarrior]

The speedo turns backwards in reverse. Most of the time it works (I don't know about accuracy) but sometimes it doesn't.

I'll pull it and clean it all but how do I clean/replace the tach and temp sensors?

Some speedos do turn backwards in reverse...not a problem....just drive thousands of miles backwards to get your truck back like new...rofl

I am not saying remove the sending units from the engine, just disconnect the wires going to them...clean those contancts and replace!

Do you know where the tach sensor is on the top of the IP gear cover? If so unbolt it and then just clean any grime on the end, then replace it.

 

[redneckaggie]

the tach sensor is on top of the ip gear tower, remove it and clean the bottom side, and make sure there is no bare wire sticking out of the top, if its bare insulate it somehome, The coolant temp sensor is in the drivers head along drivers side of the head, If you are intent on keeping factory gauges I woul just replace the coolant temp sensor if cleaning the boards doesnt work.

 

[79jasper]

Would it do any good to take the cluster apart and spray the back electrical mechanism part of each gauge with some electric cleaner? Or would that be too much work at this time..

 

[riotwarrior]

Would it do any good to take the cluster apart and spray the back electrical mechanism part of each gauge with some electric cleaner? Or would that be too much work at this time..

This is what I was saying in the beginning, remove cluster...clean the contacts where the big plug/s goes into the cluster and while at it, lube speedo calble

No need to disassemble the actual cluster it's self just clean all the contacts carefully and that should help.

Al

 

[Thefarmboy21]

Haven't had a chance to clean things yet but my tach today quit working for a while. Poured the coal to it and it just went to like 200 rpm or less and shoulda been reading about 2500 RPM. I think I cleaned the tach sender before I put the motor back in but I'll clean everything again.