Trim Gauge Goes From Down To Up Instantly

[DiverGuy]

I've been trying to diagnose an issue with my trim gauge. The gauge hasn't worked since I bought the boat about 18 months ago. It reads down all the time.

At first the trim up didn't work, only the trailer switch worked to raise it.

Last year I replaced the senders when I did a bellows job, so those are new. I also replaced the entire trim pump assembly because of some signs it was going out, so it's all new. I made sure every connector was clean and shiny when I connected it to the new pump.

Now trim up stops at 21.75 inches (after I adjusted it a little). Trailer raises it full up. Trim down goes down fine.

I had my wife watch the gauge as I rotated the sender puck on the outdrive. It reads down until it reaches a certain point, then jumps to full up instantly. No in between. 2 degrees one way its full up, 2 degrees the other way its full down.

This weekend I pulled the gauge and tested it. I put power to the ignition terminal and grounded the ground terminal and it read full up (It reads full up even with no power to it). Then I jumped the sender terminal to the ground with power still on the ignition terminal and the gauge went to full down. And it was a smooth swing that took about a second to go from full up to full down. So from what I have read, that means the gauge is good.

I made sure the purple wire barrel connector and the barrel connector with two blue wires that come from the sender are solid and clean. I found the big plug with the red, green, and blue wires that comes off the trim pump and pulled it open. It was somewhat corroded. Thought I had found the culprit. I cleaned off the spades on one side and did my best to clean out the slots in the other side. Reconnected it and still no change.

Anyone have any more ideas on what to check? I've been working around it just by listening for the change in the pump sound, but that's not always easy to hear. It would be nice to have an idea where my trim is.

 

[Thornton69]

Did you use the OEM sender? A few years ago I had trouble with the Sierras. First one lasted 2 outings. It was replaced under warranty and the replacement did similar to what you are describing. Threw them both in the trash and installed OEM. They have been trouble free for past 3 seasons. Pretty sure I thought I was going to save only $40 or something like that. Instead threw away $140 and several hours of my time.

 

[scoflaw]

Gauge works in conjunction with the puck which is a rheostat. So you should have partial voltage when the drive is in between up and down

 

[DiverGuy]

Did you use the OEM sender? A few years ago I had trouble with the Sierras. First one lasted 2 outings. It was replaced under warranty and the replacement did similar to what you are describing. Threw them both in the trash and installed OEM. They have been trouble free for past 3 seasons. Pretty sure I thought I was going to save only $40 or something like that. Instead threw away $140 and several hours of my time.

Used Quicksilver Part 805320A03.

 

[DiverGuy]

Gauge works in conjunction with the puck which is a rheostat. So you should have partial voltage when the drive is in between up and down

So to test that, do I stick the voltmeter probes to the sender wire and ground wire behind the gauge and check voltage while the trim is raised up and down?

 

[scoflaw]

Yes

 

[Jeff Delbuono]

Just had same problem. Pull the 4 screws from the puck. Pull out center and you will see 2 wires with contacts. 1 of my contacts was rotten. Thus would make guage jump from down to up with not gradually going up. Replaced the 2 contacts and works perfect now

 

[Thornton69]

So to test that, do I stick the voltmeter probes to the sender wire and ground wire behind the gauge and check voltage while the trim is raised up and down?

Did you mean multimeter? With your probes as described, you will have a better result if using an ohm meter. The trim sender closes the ground circuit for the gauge. Disconnect the S wire at gauge and (test on the 200 ohm range) check between it and the gauge ground to avoid running power through your meter. There is also a timing mark on the sender that needs to be aligned before installation, but am sure you know that already.

 

[scoflaw]

You could even use a plain ole test light

 

[ttmott]

The trim sensor needs to be compatible with the gauge. Otherwise it'll do exactly what you are seeing.

 

[DiverGuy]

Just had same problem. Pull the 4 screws from the puck. Pull out center and you will see 2 wires with contacts. 1 of my contacts was rotten. Thus would make guage jump from down to up with not gradually going up. Replaced the 2 contacts and works perfect now

Good to know. I'll check, but the senders are new. Replaced them last year and only used in fresh water since.

 

[DiverGuy]

Did you mean multimeter? With your probes as described, you will have a better result if using an ohm meter. The trim sender closes the ground circuit for the gauge. Disconnect the S wire at gauge and (test on the 200 ohm range) check between it and the gauge ground to avoid running power through your meter. There is also a timing mark on the sender that needs to be aligned before installation, but am sure you know that already.

Yes, I should have said multimeter. Thanks for the details. I'll try it this evening.

And yes, I think I know about the timing mark on the sender. When you pull the puck off the outdrive, around the hole where the asterisk-shaped hub sticks out, there is a small mark at the edge of the hole that is raised. And at the end of the hub itself, one of the points of the asterisk has a slight protrusion that sticks up. That protrusion needs to be aligned with the mark at the edge of the hole. I'm guessing that's what you mean. It took me a while to spot the part that sticks up from the tip of the asterisk.

 

[DiverGuy]

So if I combine what Thornton69, scoflaw, and ttmott said, I should set my multimeter to ohms (it's auto-range so I can't select 200 watt range), disconnect the sender wire from the back of the gauge, touch one probe to the sender wire and one to the gauge ground. At full down trim I should see about 10 ohms, then trim up and I should see it rise to about 167 at full up trim.

I'm guessing that 167 is at full up, not at full trailer position, correct?

If I'm getting the proper readings at the wires that connect to the gauge, then a bad or incompatible gauge is the only remaining option, correct?

 

[DiverGuy]

I did some testing this evening and believe I may have two problems.

The trim sender wire runs through the transom and has two barrel connectors in the engine compartment that plug into the connectors labeled Chassis Ground and Analog Trim. I unplugged those and connected the positive terminal of my multimeter into the one that connected to Analog Trim and the negative terminal of my multimeter into the one that connected to Chassis Ground (so my multimeter is connected directly to the trim sender) and turned it to ohms. At full down, it read 9.8. At full up trailer position it read 171, so pretty close to the chart that ttmott posted above. So my sender should be good.

I pulled the gauge but left the ignition wire attached. I ran wires from the barrel connectors that I had my multimeter connected to, and ran the trim signal wire to the signal pole on the back of the gauge, and the ground wire to the ground pole on the back of the gauge, then switched the ignition switch on so the gauge had power. No matter which way I moved the trim, the needle didn't move from full up. So even though the gauge passed the test I described in my first post, I think this gauge is bad. Just to retest it, I disconnected the signal wire and connected the ground pole to the signal pole on the gauge and the needle swung to full down. Even though my ohmmeter is showing varying ohms at that point, the gauge doesn't move.

So then I decided to check the ohms behind the dash. With my ohmmeter connected directly to the barrel connectors in the engine bay, I was reading 92.7 ohms where the trim was set. I disconnected my ohmmeter positive wire and reconnected the signal wire to the Analog Trim connector, left my negative wire on the ohmmeter connected to the barrel connector for the ground wire from the trim sender, then touched my positive wire from my ohmmeter to the signal wire behind the dash. It read 92.7 ohms again, so my signal is getting to the dash. Then I disconnected my negative wire of the ohmmeter from the barrel connector of the trim sender ground wire, and reconnected the trim sender ground wire to the Chassis Ground connector in the engine bay, then touched my ohmmeter negative wire to the ground wire behind the dash. So now my ohmmeter is connected to the signal and ground behind the dash, and it reads 57 ohms. A drop of about 35 ohms. So I'm thinking I have a ground that's not strong somewhere.

So I think I have a bad gauge and a bad ground. If someone disagrees please correct me. And if anyone has suggestions on places to check grounds that affect the trim sender, please pass them along.

Sorry for the long post. I just want to be detailed so that maybe this helps someone else in the future with a similar problem.

 

[Thornton69]

Your terminology is a bit tough to follow. Here are the installation instructions.
https://www.perfprotech.com/store/app_themes/ppt/images/product-specs/trim-sender.pdf
Page 7 shows the timing (index) marks that I was referring to while drive is in the full down position. I just checked a 3 season old along with a new out of the box sender. They both show about .5 ohm in the indexed position. When the drive trims up, the resistance increases. Sorry, mine is apart at the moment or I would just give you my readings for a reference.
Confirm your values at the gauge with at least the Signal wire disconnected. There should only be a slight increase in resistance from what you recorded at the transom if there is any. If the readings are the same then the wiring is good. Checking the resistance while the wires are hooked up to the gauge (gauge is now a parallel circuit) will decrease the resistance you are reading.
Don't be afraid to move the little rotor slightly out of the index position if you don't have enough adjustment in the sender body slots to please your gauge.
Edit: Don't worry about the part number on these instructions, it is superseded by yours.

 

[DiverGuy]

Your terminology is a bit tough to follow. Here are the installation instructions.
https://www.perfprotech.com/store/app_themes/ppt/images/product-specs/trim-sender.pdf
Page 7 shows the timing (index) marks that I was referring to while drive is in the full down position. I just checked a 3 season old along with a new out of the box sender. They both show about .5 ohm in the indexed position. When the drive trims up, the resistance increases. Sorry, mine is apart at the moment or I would just give you my readings for a reference.
Confirm your values at the gauge with at least the Signal wire disconnected. There should only be a slight increase in resistance from what you recorded at the transom if there is any. If the readings are the same then the wiring is good. Checking the resistance while the wires are hooked up to the gauge (gauge is now a parallel circuit) will decrease the resistance you are reading.
Don't be afraid to move the little rotor slightly out of the index position if you don't have enough adjustment in the sender body slots to please your gauge.
Edit: Don't worry about the part number on these instructions, it is superseded by yours.

LOL!! I think the word "terminology" is being kind. I figured I would probably lose some people trying to describe what I was doing.

I know the timing indicators you described. Mine were not perfectly aligned, they were off by about the width of the mark. When I aligned them perfectly it did read near 0 ohms. I left them where they were because it read close to 10, which was what the chart above showed as minimum.

When I checked ohms at the gauge, I had the gauge disconnected and just had my ohmmeter touching the signal and ground wires. That is when I got a lower reading than what I got when connected directly to the wires off the sender.

I went ahead and ordered a new trim gauge. My old one has a lens that's hard to see through anyway, so even if it doesn't fix my problem its not really a waste. I'll see what happens when I hook it up.

Thanks again for the help.

 

[DiverGuy]

The new trim gauge worked. I guess the test of shorting the sender post to the ground post and seeing if the needle moves doesn't necessarily mean that your gauge is good after all.