Low sensor voltage

[chucknovice]

New poster here, but long-time lurker. Thanks for all the help over the years!

I've had my 2001 for ten years and it's always run noticeably rich. I finally decided to try figure out why, so I pulled off the airbox to check for cracked vacuum hoses. While I'm in there, I check the intake air temperature sensor and intake air pressure sensor. Both voltages should be 4.5-5.5 with the ignition on, but I'm reading 0.2V on both!! No codes are showing up...

I tried a different multimeter, same thing, 0.2V. Checked continuity back to the ECU plug, all good.

Now what??

Thanks
Matt

 

[202mphbusa]

New poster here, but long-time lurker. Thanks for all the help over the years!

I've had my 2001 for ten years and it's always run noticeably rich. I finally decided to try figure out why, so I pulled off the airbox to check for cracked vacuum hoses. While I'm in there, I check the intake air temperature sensor and intake air pressure sensor. Both voltages should be 4.5-5.5 with the ignition on, but I'm reading 0.2V on both!! No codes are showing up...

I tried a different multimeter, same thing, 0.2V. Checked continuity back to the ECU plug, all good.

Now what??

Thanks
Matt

View attachment 1668062

Connector UNPLUGGED
One lead to each should be about 5v that is the feed to the sensor
each has a ground
then the third wire to each goes back to ECU

 

[Kiwi Rider]

Now what??

Thanks
Matt

Hey Matt, have you tested continuity from the red wire (4.5v power feed from ECU) on the connector plug all the way back to the ECU?
Have you checked voltage (4.5v) probing the connector terminals +probe to Red, -probe to B/Br ?
Note, connector must be DISCONNECTED and key turned ON while testing.
Also check ECM couplers terminals number 48,54, and 58 for loose or broken connection (these wires lead back to the connector plug at the IAP sensor) and also check continuity on all 3 of these wires. Check for ground continuity on the B/Br wire, and also check if the other two (red or GB) are grounded or are open circuit.
If all these checks test OK, try another ECU, yours may very well be faulty.
Happy hunting!

Oh yeah, your bike looks great, tell us more about it and more (focused) pics please!!

P.S, I lived in Perth in the '80's, loved the place, bet it's different these days lol.

 

[chucknovice]

Hey Matt, have you tested continuity from the red wire (4.5v power feed from ECU) on the connector plug all the way back to the ECU?
Have you checked voltage (4.5v) probing the connector terminals +probe to Red, -probe to B/Br ?
Note, connector must be DISCONNECTED and key turned ON while testing.
Also check ECM couplers terminals number 48,54, and 58 for loose or broken connection (these wires lead back to the connector plug at the IAP sensor) and also check continuity on all 3 of these wires. Check for ground continuity on the B/Br wire, and also check if the other two (red or GB) are grounded or are open circuit.
If all these checks test OK, try another ECU, yours may very well be faulty.
Happy hunting!

Oh yeah, your bike looks great, tell us more about it and more (focused) pics please!!

P.S, I lived in Perth in the '80's, loved the place, bet it's different these days lol.

Hi Kiwi, thanks for the detailed response

I checked everything again this morning:

have you tested continuity from the red wire (4.5v power feed from ECU) on the connector plug all the way back to the ECU?

I checked the green/black/red on the IAP and the green/black on the IAT. Continuity all good on each wire

Have you checked voltage (4.5v) probing the connector terminals +probe to Red, -probe to B/Br ?

I get 0.17V across the IAP terminals, and 0.19V to the frame (also checked this against the battery-ve terminal):

I get 0.2V across the IAT terminals, and 0.21V to the frame:

connector must be DISCONNECTED and key turned ON while testing.

Yep, and this is what I see:

Check for ground continuity on the B/Br wire, and also check if the other two (red or GB) are grounded or are open circuit.

Checked, the black wires are definitely earthed, and the red wire on the IAP is also earthed...

If all these checks test OK, try another ECU, yours may very well be faulty.

Yeah, I hope not, that sounds expensive
The bike runs fine otherwise. Could I be getting low voltages due to an ECU tune by the original owner?

I also tested the IAT sensor resistance, 2.9kOhm at 15 degrees C.
Spec is 2.2-2.7 at 20 degrees.
Could that create rich running?

Oh yeah, your bike looks great, tell us more about it and more (focused) pics please!!

Yeah, I love the silver/blue.
Mods:
- Tail tidy (by previous owner)
- Full CNC yolk conversion (I might make a post on this)
- 4-pot Nissin calipers (those 6-pots were junk)
- Nissin semi-radial brake and clutch master cylinders
- HEL braided lines
- 2004 clutch slave cylinder, for improved sealing
- lowered footpegs
- cheapo chain guard
- removed the previous owners Blue Flame silencers, tried the OEM cans but currently running the triangular Yoshimuras

Cheers
Matt

 

[Kiwi Rider]

Hi Kiwi, thanks for the detailed response

I checked everything again this morning:


I checked the green/black/red on the IAP and the green/black on the IAT. Continuity all good on each wire


I get 0.17V across the IAP terminals, and 0.19V to the frame (also checked this against the battery-ve terminal):

View attachment 1668091

I get 0.2V across the IAT terminals, and 0.21V to the frame:

View attachment 1668092


Yep, and this is what I see:

View attachment 1668093



Checked, the black wires are definitely earthed, and the red wire on the IAP is also earthed...



Yeah, I hope not, that sounds expensive
The bike runs fine otherwise. Could I be getting low voltages due to an ECU tune by the original owner?

I also tested the IAT sensor resistance, 2.9kOhm at 15 degrees C.
Spec is 2.2-2.7 at 20 degrees.
Could that create rich running?

View attachment 1668094



Yeah, I love the silver/blue.
Mods:
- Tail tidy (by previous owner)
- Full CNC yolk conversion (I might make a post on this)
- 4-pot Nissin calipers (those 6-pots were junk)
- Nissin semi-radial brake and clutch master cylinders
- HEL braided lines
- 2004 clutch slave cylinder, for improved sealing
- lowered footpegs
- cheapo chain guard
- removed the previous owners Blue Flame silencers, tried the OEM cans but currently running the triangular Yoshimuras

Cheers
Matt

Matt, do you have the service manual (Suzuki OEM)?
If not, PM @Berlin Germany . . . he can send you a link, he has all the manuals (online) and he can probably help you further with the testing/diagnosis of your problem.

 

[chucknovice]

I

Matt, do you have the service manual (Suzuki OEM)?
If not, PM @Berlin Germany . . . he can send you a link, he has all the manuals (online) and he can probably help you further with the testing/diagnosis of your problem.

Thanks kiwi, I actually have two manuals (Haynes and “OEM”). They both just say check wiring and connector terminals, thats all.

I might try jamming some fine pins in the connectors and re-testing with the bike running. And also first check the voltage on the ECU pins, I just need to create better access…

 

[Berlin Germany]

Matt, do you have the service manual (Suzuki OEM)?
If not, PM @Berlin Germany . . . he can send you a link, he has all the manuals (online) and he can probably help you further with the testing/diagnosis of your problem.

hey dude

u didn´t check yet that all gen1 & 2 & 3 manuals are (partly here over the org) available 4 download ?

i personally saved the three links at my desktop here at home so i have em allways available

here again my three manual-links 4 everybody :

gen1 ´99-´02 (plus microfiches)

gen2 ´08-´12 (without abs ´13-´20)

gen3 ´21- today