2003 XC90 T6 intermitted won't start,new starter & battery

[cocoli2007]

Originally Posted by rapidvxr

somebody had a similar prob a while ago and i think it turned out to be gear lever boot material stopping lever going all the way home

Hello Rapidvxr,

Do you have more details info for 'gear lever boot materail...', where is it, and how to check it.

This noon, I could not start my car again, I used a jump wire to connect starter relay pine #30 and #87 directly, car was jumped, it means starter relay --> starter motor --> engine is fine. It looks like ignition switch, immobilizer, or computer has problem.

[rapidvxr]

Originally Posted by cocoli2007

Hello Rapidvxr,

Do you have more details info for 'gear lever boot materail...', where is it, and how to check it.

This noon, I could not start my car again, I used a jump wire to connect starter relay pine #30 and #87 directly, car was jumped, it means starter relay --> starter motor --> engine is fine. It looks like ignition switch, immobilizer, or computer has problem.

hi , sorry i spelt it wrong , its the gear lever boot , other forum member had similar issues with random non start , lots of posts going backwards and forwards with people trying to help , it turned out he had replaced the gear lever boot but some of it was getting jammed and stopping gear lever going all the way forward , i guess there is a switch that needs to be made for the start circuit

[Moose Test]

Originally Posted by cocoli2007

how to check it.

Simple. Next time it doesn't start, immediately turn the key back to the '0' position and try to take it out. If it won't come out, then the car does indeed think that it is not in park and that would explain why it won't start. If the ignition key will come out, this isn't your problem.

Originally Posted by cocoli2007

It looks like ignition switch, immobilizer, or computer has problem.

Which is why, as Swiss as already said, you should now take it to a Volvo dealership or specialist, who has the software to correctly diagnose this.

[cocoli2007]

Originally Posted by Moose Test

Simple. Next time it doesn't start, immediately turn the key back to the '0' position and try to take it out. If it won't come out, then the car does indeed think that it is not in park and that would explain why it won't start. If the ignition key will come out, this isn't your problem.


Which is why, as Swiss as already said, you should now take it to a Volvo dealership or specialist, who has the software to correctly diagnose this.

Today, I measure the voltage on ignition switch output Y-W cable, which is connected to CEM, it is 14.2v when starting (failure). Then I measure two control sports for starter relay, one is always 0, one is sometime 14.2v, most of time is 0.

See attachment wiring diagram of 2003 XC90 starter. Sounds CEM has problem.

[SwissXC90]

Originally Posted by cocoli2007

Today, I measure the voltage on ignition switch output Y-W cable, which is connected to CEM, it is 14.2v when starting (failure). Then I measure two control sports for starter relay, one is always 0, one is sometime 14.2v, most of time is 0.

See attachment wiring diagram of 2003 XC90 starter. Sounds CEM has problem.

At this stage you really need to use VIDA to get a proper diagnosis.
Everything else is guessing

You can, if you wish, replace the CEM. Needs to be programmed by a dealer and will cost you quite a few hundred GBP, maybe even a thousand GBP

That's why I recommend using VIDA.
Check all start inhibit systems carefully for proper, reliable function
Especially the gearbox start inhibit system

[diro]

If there is CEM problem (and in many cases like that it is) Vida will show nothing related to no starting issues. Starter motor is controlled by CEM.
Quick test if the same problem occurs - leave ignition on, get a single cable and wake up a starter motor simply connecting 1 cable end to battery positive and the other end to the starter bendix solenoid wake up terminal.
Other way is to bypass starter motor relay shorting relay socket terminals 30 and 87 if I remember. It depends on the relay terminal layout
If starter motor cranks but engine wont start - its most likely CEM problem. Has to be replaced/cloned. I would also give a shot replacing ignition switch first as its cheap but wouldnt expect too much

[cocoli2007]

Originally Posted by diro

If there is CEM problem (and in many cases like that it is) Vida will show nothing related to no starting issues. Starter motor is controlled by CEM.
Quick test if the same problem occurs - leave ignition on, get a single cable and wake up a starter motor simply connecting 1 cable end to battery positive and the other end to the starter bendix solenoid wake up terminal.
Other way is to bypass starter motor relay shorting relay socket terminals 30 and 87 if I remember. It depends on the relay terminal layout
If starter motor cranks but engine wont start - its most likely CEM problem. Has to be replaced/cloned. I would also give a shot replacing ignition switch first as its cheap but wouldnt expect too much

Hi,

I did to bypass starter motor relay by shorting pin 30 and 87 a couple of times, car was started successful.

Regards.

[diro]

Originally Posted by cocoli2007

Hi,

I did to bypass starter motor relay by shorting pin 30 and 87 a couple of times, car was started successful.

Regards.

Good.
for the peace of mind you could try few more times shorting pins but i think its not necessary. Its not CEM
I just took a look at the wiring diagram you attached and am pretty much sure it is the wire which intermittently supplies positive to the starter relay pin 86. Following the diagram if you take a look there is digit "4" in the grey background square. That is a wiring harness connector. It can be problem there - corroded, bad contact. Or the wire itself from that connector to the relay.

I also would not rule out ignition switch and you know why?
Because there is possibility you moved wires/terminals a little bit on the ignition switch and it was just enough to have a constant positive while you been checking voltage

Have fun

[cocoli2007]

Originally Posted by diro

Good.
for the peace of mind you could try few more times shorting pins but i think its not necessary. Its not CEM
I just took a look at the wiring diagram you attached and am pretty much sure it is the wire which intermittently supplies positive to the starter relay pin 86. Following the diagram if you take a look there is digit "4" in the grey background square. That is a wiring harness connector. It can be problem there - corroded, bad contact. Or the wire itself from that connector to the relay.

I also would not rule out ignition switch and you know why?
Because there is possibility you moved wires/terminals a little bit on the ignition switch and it was just enough to have a constant positive while you been checking voltage

Have fun

I did not find "4" connector location, is it the one plug in CEM board?

These days, it works fine. I wanted to test the Gn-R cable which connects to fuses box if start is failed, to make sure the fuser board itself is ok. then next step is removing CEM to check any corrosion and clean it.

[SwissXC90]

My vote is still the start inhibit switch on the auto gearbox

Pin C:28 on the CEM, a BL-Y wire heading to switch 8:37 on the auto gearbox

Pin C:28 is switched to ground
Not sure of the logic: either C:28 is grounded to inhibit start, or to enable start. One or the other.

But worth checking this

If the gearbox is not in P or N you cannot start the engine and the symptoms are identical to your descriptions. No messages are shown, no clicks are heard from the starter, nothing happens when key is in PosIII.

Check by trying to turn off ignition and remove key WITHOUT touching the gearbox level at next failled start attempt. If you CANNOT remove the key, the car thinks the gearbox is in something other than P or N, thus preventing key removal and preventing start.