Hi guys and girls,
Try as I might to find anyone else who has had this problem I can't

Plugged MES in today and had a handfull of codes relating to low voltage and sensors. Looked at ECU readings and its seeing 3.84v at ecu and battery voltage at pin 15.... unplug ecu and test at connectors still seeing 3.8v. Something is wrong. I assume the ecu should be fed battery voltage where im seeing 3.8v

Does anyone have a wiring diagram they could email me?

richydraper said:

Hi guys and girls,
Try as I might to find anyone else who has had this problem I can't

Plugged MES in today and had a handfull of codes relating to low voltage and sensors. Looked at ECU readings and its seeing 3.84v at ecu and battery voltage at pin 15.... unplug ecu and test at connectors still seeing 3.8v. Something is wrong. I assume the ecu should be fed battery voltage where im seeing 3.8v

Does anyone have a wiring diagram they could email me?

Click to expand...

whats your main battery voltage ?

13.6v when on tickover.

richydraper said:

13.6v when on tickover.

Click to expand...

sounds a bit low without anything turned on, plenty of posts on here about sterring problems, most of them relate to main battery on its way out, even a small voltage variation can cause problems

Battery's good... my main concern is the <4v where id expect to see batt. voltage

ecu talks to bsi for vss what voltage do you want it to talk to in?
do you understand the can network workings?
i dont profess to but i dont prod snakes with sticks either

s and b said:

ecu talks to bsi for vss what voltage do you want it to talk to in?

Click to expand...

I don't think thats what Richy is on about, the EPS ECU is reading a voltage of only <4V at the EPS unit, not what the Body Computer is telling the EPS Ecu the car is running at.

Most Easterly Pandas said:

I don't think thats what Richy is on about, the EPS ECU is reading a voltage of only <4V at the EPS unit, not what the Body Computer is telling the EPS Ecu the car is running at.

Click to expand...

theres a big beefy connector goes to ecu with 12 volts ,that cant possibly give anything less

How are you testing these voltages? And where are those wires coming from, obviously if its connected to a sensor the sensor my influence the voltage and consider that they may already be 5volt lines for logic (canBus)

If the ecu is only being powered with 3.8volts then its unlikely to work as this wouldn't be enough to power the chips in the ecu, so I suspect its still getting a 12v feed from somewhere

You need to be a bit more specific as to what the fault codes actually said

nope dont care about CAN, maybe i should have explained a little better... above is an EXAMPLE of the figures i was seeing... obviously the permenant ECU supply is there at Batt.+ (+15 if you prefer) but surely i should be seeing greater than the 3.84v at the 'ECU supply voltage'. in addition to MES showing the 3.8v i also disconnected the steering unit and tested the wiring to it this was showing 3.8v i cant for the life of me remember which pin it was i tested but it WAS NOT a can line. i think it had the thicker gauge wire running to it.

my question is... what could cause this drop in supply voltage??

am i right in thinking that it would be fed from a relay? if so is this relay behind the power steering motor/engine bay fuse box/somewhere else.

im familiar with the Mk2b steering and had to replace a battery on one that had an intermittent fault. i know how tempremental the systems are on the puntos and know that the usual route of fixing it is check battery>check relay>replace unit. im pretty convinced that, for now at least, its not the steering unit gone pop. obviously i want to sort the supply issue before any further diagnosis

Hi, I have to refresh this topic cause I have similar problem. One day my power steering said stop. MES showed error c1008 (but it's not popular issue so I couldn't find more info). I saw that MES shows 0,0 angle when I try to twist a steering wheel, but potentiometers works good and these shows voltage 0-4V (I think it's to little)

The most important is that MES showed voltage on ECU about 12V on ignition position

but when I turned on engine it showed 3V ?! WTF?!


How author of this topic solved the problem?
And BTW: voltage on battery is 13V, when engine is on 14V
Can someone compare it?

14V when engine is on is good, so its not your alternator

try with another pas motor first, then ecu and if its still same then its sensor which involves removal of steering column

I see that angle sensor is working when it has 12V (values of potentiometers are changing), when ecu has 3V - values are not changing. But main question is
when i'm connected with delphi module of power steering the row of "ecu supply voltage" shows supply of delphi module? Am I wrong?

dunno about that, everytime i had non working pas car i tried with parts that are easier and faster to change, never checked with mes cuz before laptop would start up i would already switch pas motor
what year is your punto?

I disassembled EPS and I checked relays on motor - one of them is damaged, then I measured voltage on permanent + and after ignition + and on both of them there is 12V supply. So I have no idea why ecu sends info about 3V (and why it sends info to EPS?)

blue or yellow sensor cable? year of car?

The blue one, 2000 year.


I found similary thread on polish forum, user had same problem with voltage - he replaced module of EPS and that was all.

I'll try to contact with him, but it could be hard to do, cause polish forum of punto is dead.

change pas motor

SOLVED
I swapped both relays on replacements, now everything works fine, and ecu supply voltage is ~13V when Motor is on

thanks for showing interest

Hi I tried with alfaobd see the results it says system disabled. so how to enable this.


c1008
Motor phases
Open circuit
Failure lamp 'ON': Requested
Fault present
Test complete or not applicable
Battery voltage: 11.73 V
Recovery type: System disabled
Effort on steering wheel: -0.14 Nm
Vehicle speed: 0.00 km/h
Calculated steering position: 0.00 °
Motor control current: 0.00 A