1999 optimax 150 TPS alarm

[psrl]

1999 optimax 150 hp s.nr.: 0G802873

Hi.


Having trouble understanding this alarm im getting.

I have a check engine light and a intermedient alarm...beep...beep...beep, rev limiter 3000rpm. Alarm doesnt stop until i stop the engine.

Tried to adjust roller cam with no luck. I read 0,300volts on outer TPS and 4,4v on inner. They are both within spec and seems fine all the way to WOT.

If i disconnect the TPS and use a digital voltmeter on the connector, i have 4,6v and 4,9v on connector c and b, a is ground (black) on the outer TPS, The inner is just 4,9v on ONE connector... should they be the same?

If i disconnect throtle wire and slowly adjust throttle lever with the stop screw, the alarm will stopp after a slightly rpm increase. I leave it as is, stop and start, and the alarm returns....

I disconnectet the balljoint arm to the camshaft, and let the TPS rest on its body, then they wount respond at all. But if i hold the TPS arm slightly over the dead end, it will bring back som throtle respons, but still the alarm. Did this with the voltmeter connected, and the readings was all the time within spec.

As far as i can see the TPS` are fine...am i wrong? They arent cheap, so I will be 100% sure before ordering...
What else can set of an alarm like that? According to the alarm code schematic, it is clearly a TPS alarm, but my experience as a mechanic tells my this can be misleading and there is an other fault that trigger this alarm aswell....


Best regards the frustrated Norwegian

[JOE54]

my serv manual is loaned out for your engine so i cannot verify your question , though i almost sure they should be same

[EuropeanAM]

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

Make certain that the throttle is AT THE IDLE STOP when you turn the key ON, and when you start the engine. ANY input can cause a "mal-adapt" to occur.

Have you had the faults read/printed (as well as the Run History)?

[psrl]

I will update with the serial number 👍👍

I have adjusted the camshaft/throttle cable after the service manual. And with a 2 turn preload on the wire.

When it's idleing the alarm sounds.. If give a little throttle, guessing 800-1000rpm, the alarm stops. Then tried to adjust idles top screw up until alarm stops. Then stop and start engine again. The engine accept the position as new idle, and idle low and nice. But alarm is back.

I messured the tps with and without engine running, and they are both within spec... 🤔

[EuropeanAM]

Keep in mind that there are a couple dozen items that can cause that particular alarm, and active Engine Guardian. A variety of other sensors (temp, air compressor temp, MAP, shift position switch, Intake air temp, oil level, water in fuel, etc). Possibly not caused by the TPI's at all (as you've probably found, one is "increasing" voltage, the other is "decreasing" voltage).

[psrl]

That is what I suspect aswell... I've tried to unplug and "jump" a few sensors. Will do some more testing during the weekend.
Just replaced the direct injectors and mounted CCM reeds and stuffer kit, so I hope to start it up tomorrow.
Build a simple injector tester and checked the new (blue) injectors before installation ��

[psrl]

still beeping\check engine, took out the TPS` and removed the returnspring assambly on the TPS arm. swoped the inner\outer TPS. hooked up a voltmeter, still within specs..

Now i cant understand why the outside TPS is twice the price... they are the same, only opposite arm-movment... ??

good stream from indicator wateroutlet, unhooked every sensor to see if i can stop the alarm. jumped them with a pice of wire...

alternator volt is 14,4v from idle.

if i just increase the rpm slightly, the alarm stops....

[EuropeanAM]

The TPS with decreasing voltage has not been used in many years. The INCREASING voltage TPI is quite common, even used today in one engine model. Thus, it's going to be less expensive.

[psrl]

Yes, but I opened the return-spring assambly, mountet it back the opposite way on the opposite TPS, and they changed from outer to inner in voltage readings...

Anyway, is there a detailed electric schematic to find somewhere online. I have the one from the service manual, but I would like some more details... Like expected voltage from ecu on the different connections, what every signal, should look like...

I'm kind of lost in the dark now... Every sensor I test is within spec. Temp sensors are OK, tps are OK, swop inner tps with the outer to test them on the other end of their range, still within spec. Water is OK, jumped the neutral switch, water in fuel sensor, coils test OK, injectors ok,
The only thing I haven't tested is the map, crankshaft position sensor, and manifold temp, can't find the values for them....

[psrl]

Cant find any faulty sensor or function, so im back on the TPS`. When i disconnect the inner TPS, the engine dont respond on any throttle. If i disconnect the outer TPS, nothing changes, runs good, and respond to throttle.
So i decided to replace it, and my curiosity had to look inside... foud a small area where there was some (damage tear\rust\short?)

so the new question is. My TPS has the number 832952-2 and its the one increasing the voltage. If i search ebay for 832952, i find alot of TPS` but most of them have another number in the end (832952 xx). They all look the same, and if they all are increasing the voltage, is it possible i can use them? The original mercury is expensive so i hope i can use one of the other merc TPS with the 832952 number...?

[EuropeanAM]

The service manual is the best and most detailed service information for your engine.

Don't look at numbers found on parts. Look them up in the Parts Catalog, and have a local dealer obtain the latest and greatest part or component for you.

The TPI's are not interchangeable, not even if you reverse the springs. Given what you've done so far, I'm going to suggest you obtain BOTH units, the lever, and replace them.

8M6005166 (OUTER TPI)
8519371 (LEVER)
8M6005905 (INNER TPI)
850882 (SPACER).

The above are the part numbers you need.

Note: Per the Forum Announcements, we do not support parts or components sourced from, or purchased from the "bay".

[psrl]

Tried a set of TPS today, still same problem. But there is something about the messurments i dont get.

The A pin is ground. C pin is 4,7v in to sensor. And B pin is signal out, from TPS to ECU. But if i messure on the outer TPS, the B pin shows 4,6v.... shouldnt this be voltage free when i messure direct on the wireing harness without the TPS connected?

[EuropeanAM]

There is no manual-documented test for the above. Are you saying you have 4.6 VDC on BOTH pins B and C with the TPS disconnected from the connector?

[psrl]

Yes. But when I connect the TPS with a small wire in the connector, the reading is correct. One TPS increasing, the other decreasing...

[lpugh]

If I understand your statements correctly
You sir may have a open ground ckt on the latter sensor. If the signal ckt has the same voltage as the reference that means there is no voltage drop across the resistor, all points on the resistor will measure high voltage A to C is wiper type resistor and must have good ground for the wiper to have variable voltage, Do not jumper a ground to this circuit as it is an isolated delicate circuit in the computer butt should be common to all sensors implying a broken wire or failed splice somewhere

Dual sensors are fairly common in the automotive field for TPS and accelerator pedal sensors in all cases they are mirrored, meaning one high to low and the other low to high so this also means pin B on the sensors will be opposite at closed or open throttle, there is center point in which both sensor will read the same at about 2.45 volts give or take a tenth
Only two ways to check this sensors accurately, with a scan tool that can perform a sweep test or a lab scope

Hope you were able to follow this, be very careful testing the 5 volt reference ckts as the PCM is at risk
10 meg ohm dvom or scope only

[psrl]

After a night thinking I got to think about one thing, if I remember correctly, the ground wire for one of the TPS is common ground for. Lot of sensors on the engine. So if one or more sensors malfunction ir can give a misreading to the other sensors using the same ground?

Could I make a temporarily ground to check if the TPS will work?

The A pin, which is the blk/yel wire. this is equal to ground on the inner TPS, but on the outer it shows 0,6v between A pin when ignition on.....

getting really confused about this now....

[psrl]

just adding some info after some hours of troubleshooting.

If i disconnect the throttle arm between the TPS` and the throttleplate. The engine will beep when start up, when i rev it just over idle (approx 1000rpm) the alarm stops. going back to idle and alarm is back. (the TPS goes further back when disconnected from throttle arm.
Adjusted throttle cam and arm according to manual.
Voltage from alternator is 14.6v-14,7v at idle and 1000rpm.

When i disconnect the outer TPS nothing changes... if i disconnect the inner TPS there is no throttle respons.
its on the outher TPS i have .6v between engine block and ground cable on TPS connector...

disconnected, cleaned and lubed all ground connections on the engine.

Starting to worry about the ECM gone bad...

[EuropeanAM]

When i disconnect the outer TPS nothing changes... if i disconnect the inner TPS there is no throttle respons.
its on the outher TPS i have .6v between engine block and ground cable on TPS connector...

PLEASE STOP PROBING AND TESTING BEFORE YOU DAMAGE OR DESTROY YOUR PCM (hopefully it is not already damaged).


You CANNOT test 5V reference circuits using ENGINE GROUNDS as that would be MIXING voltage reference circuits, which can damage the PCM in literally moments.

Disconnecting sensors will generate faults and/or limit engine RPM's.

Disconnecting LINKAGES will result in readings that are outside of the PCM's pre-programmed tolerances for the sensors.

[psrl]

Update:

Replaced ECM, now it runs perfect!!

[EuropeanAM]

Glad to hear you're back up and running. Hate you had to buy an ECM/PCM, but sometimes there's just no option.