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I made a fatal error while checking the right side electrical stuff and relays: I forgot to disconnect the battery: a short-circuit happened and then I get no more electricity on the central console.
Every fuse is ok (left/right and central)
However no illumination of the button, no power for the blowers, none of the air conditionning buttons is working.
I have read all the related wiring diagram found thru this forum but I failed to understand where to search.
I would be delighted to receive directions for searching and finding the culprit, as my garage has started to spend hours behing the central console and around.
Cheers.
The power for the climate control system and radio comes from Fuse 10 in the right fuse box, by way of the A/C and Radio Relay, which is mounted behind the glove box. Try replacing Fuse 10 even if the one in the fuse box looks OK. Check the fuse connectors in the fuse box for discoloration from arcing and clean if you see any. If that doesn't work, suspect the A/C and Radio Relay. Another possibility is a problem inside the fuse box due to the short. Cold and broken solder joints are common on the fuse box circuit boards.
You can download the 1989 XJ Electrical Guide at the link below, courtesy of our forum member Gus:
Thanks Don for the indicated paths. I will do the checks this morning with the garagist . I'll let you informed of the results.
Cheers
I stopped the garage to dismantle everything under the dash and central console because they where not able to find the causes.
They noticed that the resistor of the right blower was located outside the blower (as weel as the relays) and they warned me that this location near all the other cables and relays and ECUs could led to a fire due to the high temperature of the resistor.
Does someone have an idea of the resistor temperature when the blower runs at low or medium speed? or confirm the fire risk?
They noticed that the resistor of the right blower was located outside the blower (as weel as the relays) and they warned me that this location near all the other cables and relays and ECUs could led to a fire due to the high temperature of the resistor.
Does someone have an idea of the resistor temperature when the blower runs at low or medium speed? or confirm the fire risk?
The blower speed control circuit in the XJ40 is not actually a resistor. It's an NPN Darlington transistor wired to act as a variable resistor. The large resistor in the circuit is just there to protect the transistor from voltage spikes produced by the motor. The circuit board was originally mounted on the inside of the blower housing, but because they were susceptible to corrosion in that location, many owners who rebuilt their failed circuit boards opted to mount them on the outside of the blower housing. I've never heard of one causing a fire or any other issue.
However, I'm wondering if what your shop actually saw may have been a temperature sensor mounted on the blower recirculation flap? And on an '89 there may also be some original relays mounted on the exterior of the blower housing. I can't recall for certain.
The blower speed control circuit in the XJ40 is not actually a resistor. It's an NPN Darlington transistor wired to act as a variable resistor. The large resistor in the circuit is just there to protect the transistor from voltage spikes produced by the motor. The circuit board was originally mounted on the inside of the blower housing, but because they were susceptible to corrosion in that location, many owners who rebuilt their failed circuit boards opted to mount them on the outside of the blower housing. I've never heard of one causing a fire or any other issue.
However, I'm wondering if what your shop actually saw may have been a temperature sensor mounted on the blower recirculation flap? And on an '89 there may also be some original relays mounted on the exterior of the blower housing. I can't recall for certain.
Please keep us informed.
Cheers,
Don
Thanks again for your permanent attention from neophytes!
is the picture attached an NPN Darlington transistor? I don't think so.
Thus what is it and is it a fire risk to locate it outside the right blower as warned by my garagist?
That is the rear side of the speed control circuit board. The Darlington transistor is mounted on the other side of that circuit board, on the inside of the blower motor housing. What you see in the photo appears to be two inductor coils on either side of a large power resistor. They are either for suppressing voltage spikes from the motor or for suppressing electromagnetic noise.
Originally there was a thin black plastic cover over the parts in your photo but the cover has apparently fallen off or been removed. You could cover those components with some duct tape or electrical tape to help protect against electrical shorts. No need to worry about heat or fire.
On my car the left and right fuse boxes are numbering the fuses as A1 to A8, B1 to B8 and C1 to C8.
What do you mean by F10?
I check the right fuse box for cold or broken solder: no such case!
Will check the A/C and Radio Relay tomorrow.
Originally Posted by Don B
Hi CHELMI,
The power for the climate control system and radio comes from Fuse 10 in the right fuse box, by way of the A/C and Radio Relay, which is mounted behind the glove box. Try replacing Fuse 10 even if the one in the fuse box looks OK. Check the fuse connectors in the fuse box for discoloration from arcing and clean if you see any. If that doesn't work, suspect the A/C and Radio Relay. Another possibility is a problem inside the fuse box due to the short. Cold and broken solder joints are common on the fuse box circuit boards.
You can download the 1989 XJ Electrical Guide at the link below, courtesy of our forum member Gus:
I realize my mistake. I referenced the 1989 Electrical Guide, but since you are in France, your '89 is the equivalent of a 1990 U.S. specification car.
Referencing the 1990 Electrical Guide, the fuse you are looking for is number C1 in the right fuse box.
unable to locate the A/C and radio relay on my car
I can see a short length of the harness going outside of the blower.
From the electric diagram I understand that it is going to the climate control microprocessor.
But I can't find or identify the A/C relay which is connected to the same climate control microprocessor.
Does the relay' base have a specific color?
Shall I extract the aluminium component on the left side of the blower to find it?
Last edited by user 797820802834; Oct 7, 2016 at 02:34 AM.
Reason: incomplete initial question
I can't find or identify the A/C relay which is connected to the same climate control microprocessor.
Does the relay' base have a specific color?
Shall I extract the aluminium component on the left side of the blower to find it?
Hi CHELMI,
According to the Haynes manual, the relay has a green base. I am attaching the page with the relay diagram for the '90-'92 models, but you can download most of the Haynes manual here (chapters 7 & 8 are missing):
Since a few weeks I was searching a faulty component for having lost any air conditionning and ventilation.
Finally all components are ok (fuses, relays, ac ecu)
The culprit: the climate control microprocessor ( an electronic board) has 3 connectors each with 15 male pins. Each connector is designed to connect to a female connector.
Nothing prevents to connect a wrong female connector to the ECU.
This is what happened in my car.
Based on the electric guide were colors of the cables are set, I was able to correct the wrong connection.
Instantly the whole climate control system was ok.
I recommend to physically mark the connectors to make sure of the correct matching between the ECU and the connectors.
No more electric supply on the central console
A miracle!
