Electrical gremlins and weirdness occurring on T-5R

[JohnM 855 T5R]

Hi All,

My T-5R has decided to throw a few wobblies, all in very quick succession.

1) As I put onto another thread a few days ago, the ABS and TRACS lights are on and the underbonnet diagnostic code reader is giving me 4-4-3 which is Electrical or mechanical fault in hydraulic modulator pump motor

2) The odometer, trip meter and mileage shown since reset on the trip computer are all running way too fast - in fact they are running at 1.6x speed which means they are counting Km not miles. I know there is a procedure to reset this back to miles via the underbonnet code reader. My question is, WHY did this suddenly do this of its own accord?? I didn't do anything to make it happen (Does the car pine for the fjords or something?)

3) The radio/cd has suddenly decided not to play - as in, no power, no display no nothing!. My musical tastes may be a bit esoteric but nothing that would have caused a bunch of circuits, wires and fuses to go on strike in protest.

Now, I know people say that things come in threes - but is this all just co-incidence or is there some sinister link?

Any advice gratefully received.

John

[Juular]

Given the time of year and the current weather I'd be inclined to check if your battery is on its last legs. The one on my C70 died last week and leading up to that I had a randomly illuminated TRACS OFF light followed by some random behaviour on the CD changer.

Just a thought before you go down more time consuming / expensive avenues.

[JohnM 855 T5R]

Originally Posted by Juular

Given the time of year and the current weather I'd be inclined to check if your battery is on its last legs. The one on my C70 died last week and leading up to that I had a randomly illuminated TRACS OFF light followed by some random behaviour on the CD changer.

Just a thought before you go down more time consuming / expensive avenues.

A good thought but the battery is a 77aH Bosch S5, only 4 1/2 months old and showing 12.64 Volts - perfect condition.

The radio/CD unit, as I say is acting as if there is no power at all, i.e. it won't switch on.
The trips and odometer now recording Km is the really weird one - I'll get around to reprogramming it on port A7 - but why on earth did it just decide to flip to Km. Very, very strange.

John

[Cookeh]

Have you considered a dodgy ground? Either a bolt or strap. Dodgy grounds can cause issues in otherwise entirely unrelated electrical circuits.

[JohnM 855 T5R]

Originally Posted by Cookeh

Have you considered a dodgy ground? Either a bolt or strap. Dodgy grounds can cause issues in otherwise entirely unrelated electrical circuits.

Damn cold so not done a through poke round but I've found the engine earth lead is loose where it attaches to the block - so thats a start.

I also pulled the radio fuses, gave them a clean and bingo - the radio/CD unit has come out to play again. Time will tell if that is the actual problem or some other intermittent fault.

Given the oxidation on the fuse blades, I'm going to change the whole lot throughout the car - they are cheap as chips so seems a sensible thing to do. The car spent 3 years before I bought it in covered storage which wouldn't have been good for fuses and connectors as there would have been no heat being generated to keep things free of moisture / condensation.

As soon as things are a little warmer I'll go through the electrics like a dose of salts. Who knows, that might fix the ABS/TRACS issue.

John

[Luxobarge]

I reckon you might have cracked it there - I agree with the above comments about this looking like an earth problem, and a loose engine block earth strap is a bad thing - you might find the starter spins faster now too. Also agree with your plan of changing the fuses - good preventative maintenance, as you've found one dodgy fuse logic would say that there might be more. Car covers are a mixed blessing, as you say there's a risk of moisture (particularly condensation, which is very prevalent when a cold snap turns warm and wet) being trapped under the cover doing nasty things in places you can't see.

Nice one!

[capt jack]

I wouldn't mind betting that quite a lot of cars will be exhibiting strange and random symptoms just now.

Cars, like all machines, work best when they're used frequently and serviced properly. Combine weeks and months of sitting largely idle thanks to lockdown, and the extreme damp and cold of the recent weather, it's not surprising that weird and wonderful problems will crop up.

Damp is the enemy of most things metal, electrical and mechanical, so rusty brakes and bad electrical connections are very probably going to cause more than a few questions on here.

Jack

[JohnM 855 T5R]

Hi All,

Further to my post of a short while ago, all issues have been fixed.

As mentioned, the radio/cd unit not powering up was down to the main power fuse to the unit having oxidised blades - replaced all fuses in the fusebox with new ones as they were all pretty dodgy - presto, radio is good now.

ABS and TRACS lights staying on came down to 2 issues. Firstly, the earth strap to the rear and top of the engine was very loose. Tightening that put the TRACS light out. (thanks to Cookeh for that suggestion). Then pulled the connectors on the 2 ABS control units, gave the pins a good spray with contact cleaner, a light brushing with a fine bristle brass brush then a further spray with contact cleaner , left to dry then reassembled. Bingo, ABS light now goes out as it should and fault codes gone.

The odometer and the trip computer reading in Km instead of miles was fixed by reprogramming the instrument chip using the following procedure that was posted by Matthew some years ago.

Enter Diagnostic Test Mode 5 (data readout) as follows
Put key in and turn to position II
Put the fly wire into A7
Push button five times, briefly but firmly. DTM5 should now be ready for use.
When the LED comes on and stays on, the system is ready for entering codes. We need to enter 1-2-4 for speedometer type in this manner:
Enter first digit while LED is still on. Press button 1 time
Wait for LED to go out and then come on again before entering second digit
Enter second digit while LED is on. Press button 2 times
Wait for LED to go out, then come on again. Now enter third digit. Press button 4 times.
Read off and note down the response code. It will most likely be 1-1-1 or 1-1-2 if you're in KM's
Now we need to enter DTM6 (data entry) and we only have 30 seconds from the end of the DTM5 readout to start.
Press button 6 times within 30 seconds to access DTM 6 .
Now enter the new code 1-1-4 (for miles) in the same way as you entered the previous code.
Enter first digit while LED is still on Press button 1 time
Wait for LED to go out and then come on again before entering second digit (1)
Enter second digit while LED is on. Press button 1 time
Wait for LED to go out, then come on again. Now enter third digit (4). Press button 4 times.
The light will now repeat back to you the codes you have just entered.
The light should come on and stay on, now press button for 5 seconds, release it and the LED should go out. If it does you’re done.

This worked a treat - the only odd thing was the reader said my speedo was set to code 1-6 (just two digits) so it was obviously corrupted. I can only assume that the loose earth strap might have caused a voltage spike in some way. Otherwise, it's a mystery.

John